You can hide an individual chat or group chat by long pressing on the respective chat on your mobile phone or going into the three-point menu on your desktop and selection "Hide chat".
If a chat is hidden, it will of course still exist. If you receive a message or write a message in a hidden chat, it will reappear in the overview. You can easily find the hidden chat again via the search function.
It is not possible to delete an individual chat so that it can no longer be found.
A group chat can not only be archived, but also deleted.
For each chat/group there is at least one chat administrator who can edit the chat including participants, manage the role assignment within the chat as well as delete the chat.
If you are a chat administrator, you need to select the specific group/chat, then click on the profile picture. After that, the option "Delete the group/chat" appears below.