What is a good antonym for "infest"?

What is a good antonym for "infest"? I thought of "cleanse" but I'm hoping there is a better antonym. The context I'm thinking of is when an exterminator gets rid of an insect infestation.

consider also "decontaminate" and "fumigate."

For animal pests you can see, exterminate is good. For microbes people generally use disinfect or sanitize.

"Purify" or "purge" come to mind as likely candidates.

There are many good ex- words besides exterminate (mentioned in an answer) and exterminator (mentioned in question), including: expunge, with sense "to eliminate completely; annihilate"; extirpate, with senses "to destroy completely; to annihilate" and "to pull up by the roots; uproot"; and excise, "to cut out; to remove". Other useful words include abolish, annihilate, eliminate, erase, obliterate, purge.

Eradicate is a suitable and fine-sounding word. Its senses include "to pull up by the roots; to uproot" and "to completely destroy; to put an end to; to extirpate".