abstain — If you abstain from something, usually something you want to do, you deliberately do not do it.
fail — to fall short of success or achievement in something expected, attempted, desired, or approved: The experiment failed because of poor planning.
ignore — to refrain from noticing or recognizing: to ignore insulting remarks.
lack — something missing or needed: After he left, they really felt the lack.
let go — to move or proceed, especially to or from something: They're going by bus.
lose — to come to be without (something in one's possession or care), through accident, theft, etc., so that there is little or no prospect of recovery: I'm sure I've merely misplaced my hat, not lost it.
need — a requirement, necessary duty, or obligation: There is no need for you to go there.
reject — to refuse to have, take, recognize, etc.: to reject the offer of a better job.