Undo 301 redirects

[teokolo]

I'm wondering if removing 301 redirects can cause troubles from a SEO point of view.
To be more specific, some years ago I changed directory structure from /product.html to /category/subcategory/product.html and I placed 301 redirects to reflect this change.

Now I need to come back to the previous directory structure, so I need products to be moved from /category/subcategory/product.html to /product.html .

My plan is to:
1) Remove 301 redirects, so both /product.html and /category/subcategory/product.html will be accessible
2) Add canonical tag, explaining googlebot to look for /product.html
3) Wait some weeks (months) and then maybe place 301 redirects from /category/subcategory/product.html to /product.html

Website has no external links pointing to product pages.

What do you suggest?

[engine]

Item 1 is the one i'd be concerned about as it may be seen as duplicate content.

If you have to go back, do it all at once. The problem really occurs while Google's crawl of the page is in the SERPs. Users will be slightly confused if they see a cache of the page, so i'd consider making a nocache on /category/subcategory/product.html, if you haven't already got that.

[Robert Charlton]

Definitely do it all at once as engine suggests. On the timetable you suggest, it's likely that it will be seen as duplicate content. So, you need also to be concerned about (2) and (3).

The canonical tag (#2) is a nice extra bit of safety, but I would not depend on it. It's something that can happen after your 301s are in place.

Use a 301s on your server (#3), but don't wait weeks or months. Instead, do these first, and monitor them as the redirects propagate (construct, say, a table of old and new hyperlinks in Excel to check the redirects physically), and check your redirect status codes with server header checkers.

One thing to note about the redirects that may subsequently confuse you... a few days after the redirects, if not sooner, once your link tests and header status checker show that propagation is complete, the pages should be solidly redirected, though you may also have some outliers for a while... but, and this is what might confuse you, quite often the old (redirected) pages, in addition to your new pages, can continue to appear in the serps for a while.

You can occasionally test them by clicking on them... but don't worry about them. They might stay in the index for a month or two, but if your redirects are working, and your rebuilt site gets traffic, you're fine.

Also, and this can get into a long discussion, a search for the old url (one that's been redirected) will sometimes show the url in the serps for a very long while... but again, if clicking on them takes you to the new pages, and you've checked your header statuses, all is OK.

I would try to get some of your old inbound links switched over to the links some of your main category pages once your links have been changed over. Don't push this (as that might suggest you control the inbound links), but make some efforts to get some old links updated.

[teokolo]

Thank you @engine and @Robert Charlton for your opinion.

I removed old 301 redirects, placed canonical tag and also new 301 redirects. Website is working ok so it's time for googlebot to understand what's happening. I also updated sitemap to reflect new directory structure.

Let's see what is going to happen, I hope search engines will forgive my old permanent redirects not being really permanent...

[Walt Hartwell]

I'm wondering if removing 301 redirects can cause troubles from a SEO point of view.
To be more specific, some years ago I changed directory structure from /product.html to /category/subcategory/product.html and I placed 301 redirects to reflect this change.

Now I need to come back to the previous directory structure, so I need products to be moved from /category/subcategory/product.html to /product.html .

My plan is to:
1) Remove 301 redirects, so both /product.html and /category/subcategory/product.html will be accessible
2) Add canonical tag, explaining googlebot to look for /product.html
3) Wait some weeks (months) and then maybe place 301 redirects from /category/subcategory/product.html to /product.html

Website has no external links pointing to product pages.

What do you suggest?

"Now I need to come back to the previous directory structure, so I need products to be moved from /category/subcategory/product.html to /product.html "

Now, I'm not trying to be problematic, but what the hell do you mean by that sentence?
"products" can't be itemized unless there is something more(like parameters) to product.html.
Start with architecture, develop internal linking, then think about external links.