Migrating from SAAS is something Odoo provides help for, because depending on the timing of the build differences between hosted and non-hosted versions, you may run into other problems.  

If you choose to try it yourself:

1. Make sure the saas_trial module gets uninstalled.

update ir_module_module set state = 'to remove' where name = 'saas_trial'; 

2. Allow the admin password to be reset.

insert into base_config_settings(auth_signup_reset_password) values(true); 

update res_partner set signup_type='reset', signup_token='rsvabcdefghijykalklk', signup_expiration=to_timestamp('20200411','YYYYMMDD') where id=(select partner_id from res_users where id=1); 

3. Reset the password

http://localhost/web/reset_password?token=rsvabcdefghijykalklk&login=admin 

4. Upgrade your database, by upgrading the base module either via command line or via the UI.

5. Apply scheduled upgrades via Settings --> Modules.