If you want to revoke access to authentication factors for all of your users:
Remove the authentication factor from all user security policies.
Go to Settings > Policies, and for each security policy that has OTP enabled, go to the MFA tab, scroll down to the One-time passwords section, and clear the checkboxes for the authentiation factors you want to revoke.
Remove the authentication factor from your OneLogin account.
Go to Settings > Authentication Factors, select the authentication factor, and click Delete.
If you want to give your users access to the factor again, simply add it back to your account at Settings > Authentication Factors and add it back to the relevant user policies. Your users can then re-register their devices with OneLogin from their Profile page.