Password change portal / Self password recovery APM/IRULE

It really depends what kind of authentication you are using. Unless you are using localdb for authentication, the APM doesn't actually "know" the password to reset or recover it. It just authenticates against the server you tell it to (AD, radius, ldap, etc). So you have to use that server's password reset/recovery features, which is different for every type of authentication system.

If you are using AD, this sounds like what you are looking for:

 

https://support.f5.com/kb/en-us/solutions/public/16000/800/sol16806.html