If you deactivate your profile, you won't appear in Discover and your Connections will not be able to message you.
However, your account will not be terminated and you'll be able to return to it in the future.
Go to your Feeld profile (it's the human icon in the bottom right corner).
Tap 'App Settings'.
Scroll down to 'Deactivate'.
If you just want to disappear from Discover while remaining accessible to your Connections, try hiding your profile instead.