"I forgot the admin password and there is no other admin account"

If there is no second admin account and you cannot access the UI to reset the
first, use the full reset script:

sudo /opt/bng-deploy/bin/reset-admin.sh

This is destructive. The script:

Wipes users.json — all user accounts are deleted.
Wipes sessions.json — all active sessions and bearer tokens are revoked.
Generates a new bootstrap token.
Restarts the service.

After the restart, the system is in the same state as a fresh install. Go
through the setup wizard again using the new bootstrap token to create a new
admin account.

Use this only as a last resort. Any user accounts, API tokens, and session
state that existed before the reset are permanently gone.