Welcome to the forum. The only reason I can think of for the Edit Feature icon to not be available is if you had started a new sketch or edited an existing one and not closed it. Is there any chance that that's the case here?
Save your file, close and reopen and check if you get the option back? Also check on other features in the same part? Do you've multibodies part?
BTW you can double click on the feature and then dimensions will show up in the graphics area. Then you can double click on them to change.
Thanks for the responses! The problem was that I did open a new sketch but forgot to close it. So issue solved, thanks!