1. discontinue
2. stop, cease, give up, lay off, leave office
3. step down, resign, leave, depart, pull up stakes, depart
4. take leave, leave, go forth, go away, foreswear
5. renounce, relinquish, abandon, give up, drop out
5. give up, fall by the wayside, drop by the wayside, throw in, throw in the towel, chuck up the sponge