— Command: tramp-cleanup-connection vec

This command flushes all connection related objects. vec is the internal representation of a remote connection. When called interactively, this command lists active remote connections in the minibuffer. Each connection is of the format /method:user@host:. Flushing remote connections also cleans the password cache (see Password handling), file cache, connection cache (see Connection caching), and connection buffers.

— Command: tramp-cleanup-this-connection

Flushes only the current buffer's remote connection objects, the same as in tramp-cleanup-connection.

— Command: tramp-cleanup-all-connections

Flushes all active remote connection objects, the same as in tramp-cleanup-connection.

— Command: tramp-cleanup-all-buffers

Just as for tramp-cleanup-all-connections, all remote connections are cleaned up in addition to killing buffers related to that remote connection.