The exact meaning of purge can depend upon its context. For example:
"purge the government of our enemies" — get rid of people for political reasons
"purge my closet of everything I haven't worn in a year" — get rid of undesired things
"To purge yourself of crippling sorrow, you'll need to express it." — get rid of unwanted feelings
"I'm doing a 24-hour purge and then starting a new diet." — emptying the intestinal tract
Things like the continuance of British rule in India, the Russian purges and deportations, the dropping of the atom bombs on Japan, can indeed be defended, but only by arguments which are too brutal for most people to face, and which do not square with the professed aims of political parties.
There are no more uses of "purge" in Politics and the English Language.