SUGGESTION TO CHECK
Prior to removing user from system and database, please try to resync impersonation storage.
Domain hosting creation failed:
An error occurred during domain update: An error occurred during changing of hosting settings: System user update is failed: User %username% already exists.
Initial root cause is to be researched. For some reasons user was not removed previously and still present in Plesk and OS.
Delete user manually from
psa.sys_users , from system users and from ImpersonationCache Database:
mysql> delete from sys_users where login = '%username%';
mysql> delete windows system users `%username%` and `%IUSR_Username%`
ImpersonationCache is SQLite DB located at
sqlite> delete from ImpersonationUsers where login = %username%;