Does the 'PURGE' method in HTTP only removes the object from cache memory?

I have searched for purge method but didn't found anything precise.

A purge is what happens when you pick out an object from the cache and discard it along with its variants. Usually a purge is invoked through HTTP with the method PURGE. An HTTP purge is similar to an HTTP GET request, except that the method is PURGE.

This is what I found.

That's correct, you can send the PURGE method to remove a resource from the cache. This is a example to illustrate this:

GET /article/1234 HTTP/1.1

• The resource is not cached yet
• Send request to the API
• Store response in cache and return

GET /article/1234 HTTP/1.1

• The resource is cached
• Return response from cache

PURGE /article/1234 HTTP/1.1

• API sends PURGE method to the cache
• The resources is removed from the cache

GET /article/1234 HTTP/1.1

• The resource is not cached yet
• Send request to the API
• Store response in cache and return