Of course, AWA is right, just wanted to highlight that as its very imporntant to read twice - delete the keyword everywhere.
Even when keywords have been disabled over and over, IF the keyword can gather a high enough CTR with the right mixture of ads/negative keywords, I've never seen a case where it was not salvagable due to its past history.
To see if this word is salvagable:
1. Delete it everywhere.
2. Make an exceptional negative keyword list. To do this, use the sandbox, your logs, WT, and the top 100+ serps for your keyword. Everywhere the match is not exactly what you're offering, figure out what negative keyword will make you ad not show for that query. If you aren't sure if the negative word is relevant or not, then for now, add it to the negative keyword list, you can always remove it later. Right now, we're going for highly targeted match.
Of course, if this is an exact match, then negatives don't matter - they only matter for phrase/broad.
3. Look through your past ads - did any one gather even a 0.5% CTR? If so, use the highest preforming ad first, and only the highest preforming ad - you're not experimenting to see what ad gets the highest CTR/conversion - you're seeing if a keyword is workable.
If not, do a search and analyze your competitors ads.
For phrase/broad match: Are they all using dynamic insertion? If so, don't use it - or use it creatively. If none of them are, then give it a try.
For exact match: Do not use dynamic insertion, write a great title. When you analyze your competitor's ads, refresh the page a few times so you can see all the titles/copies you're working against. You want something that stands out from everything else on the page.
4. Create a new campaign. Only have Google turned on - you need to know the exact Google CTR, the partners don't matter for this test.
5. Let the ad run.
6. If it's quickly disabled, repeat 2 & 3. If it's not, then let it get some CTR history before changing anything.