Python 3.9 is now generally available.

google.appengine.api.memcache.delete

Deletes a key from memcache.

key Key to delete. See docs on Client for detils.
seconds Optional number of seconds to make deleted items 'locked' for 'add' operations. Value can be a delta from current time (up to 1 month), or an absolute Unix epoch time. Defaults to 0, which means items can be immediately added. With or without this option, a 'set' operation will always work. Float values will be rounded up to the nearest whole second.
namespace a string specifying an optional namespace to use in the request.

DELETE_NETWORK_FAILURE (0) on network failure, DELETE_ITEM_MISSING (1) if the server tried to delete the item but didn't have it, orDELETE_SUCCESSFUL (2)` if the item was actually deleted. This can be used as a boolean value, where a network failure is the only bad condition.