I often run through a few variations when testing out ideas for multiclassing when levelling up a character, and sometimes want to build multiple levels to see how skill/feat arches will develop over several levels to see if they do what I expect.
Currently, there isn't an easy way to remove a new level except saving before you add the new one (should be standard practice anyway), but if you just want to try out a few options it's tedious to have to close the character and reload the saved version - worse if you've added several levels then realised different classes were added in the wrong order and just want to switch things around a bit.
Two things that would improve how this currently works:
1) When removing a level prompt an option to remove all feats, skills, etc associated with that level automatically
2) If a specific class/level is highlighted while the remove level is selected, it should be that class/level that is removed, rather than just the highest one. Case use - character has an opportunity to retrain and decides to remove a 1 level multiclass taken at L2 and replace with preferred class or something new. Might also consider if a different choice could be inserted into the existing build at lower levels in this way by retraining?