create user new user with password 'password';
# Optional operation: Ensure that the new user and conflicting user have consistent permissions. pg_tencentdb_superuser is a TencentDB instance; replace it as needed based on your actual situation.
grant pg_tencentdb_superuser to new username;
alter user new user with CREATEDB;
alter user new user with CREATEROLE;

drop user conflicting user;
# If the conflicting user has resource dependencies, first modify the owner of dependent objects. For example, run the following statement to change the owner of a table:
alter table table name owner to new user;