Should I update, delete and merge low ranked content on my site?

[Zivush]

Some hundreds of pages of my site ranked very low – position 30-100 .

Most of these article still contain valuable information for the readers. However, they ranked very low and aren’t targeted.
Would it be SEO beneficial to start a project of merging, deleting and updating these pages?

[justpassing]

merging

Only if the merging makes sense. Also, there is trend suggesting that Google "may" (now) like smaller articles focusing on a given theme, than a longer article which is covering several subjects (even if the subjects are related). So may be in some months, your actual low ranking pages, may start being better valued by Google. No one knows.

deleting

Since you said "Most of these article still contain valuable information for the readers", there is no reason to delete them.

updating

Sure. Updating / refreshing content is a good practice. Google likes this.