Great, that we have now the possibility, not only to create user specific definitions, but also to get rid of them, once we don't need them any longer or we want to return to the standard (you can do it here: mywords - custom definitions).
However, there seems to be a bug: I did it for a couple of entries, when i then wanted to continue, I clicked the upper checkbox to select all 15 entries, but the delete button didn't change into red and I couldn't delete. I also tried it with individual entries, but same effect.
When I click the upper checkbox for all entries, but don't delete them and go to the next page instead, it keeps the checkbox checked, but the individual entries unchecked (so checkbox is not cleared, when moving to the next page).
After having deleted items on a page, Skritter automatically goes back to the first 1 - 15 items. I would prefer, if Skritter would stay on the same page, so that one can go through all the customs definition step by step and doesn't have to start always from the beginning, once an item is deleted.

I'll add this to my list of things to do.