so testingcheatsenabled true and shift-click on object-delete it didn't work ? i'v had that happen with some items before a beehive i sold the beehive as i thought as the money went into the household funds but could still hear the bees buzzing and a set of drums my sim took out from his inventory he started to play but all i saw was invisible drums it was funny in both of those games i had the sims move to a new home for the bee one when i went to the family inventory the beehive was there sold it a.s.a.p.
for the drums again had the sims move home no drums in the inventory oh well had the sim move back to the original house lo and behold the drum kit was there and usuable again
so try to move them to a new house or boat and see if the easel is usable again or if it tuns up in the family inventory or go to edit town move out move back in if the move out move back in works for you then save your game with a new name