Removes the specified user from the system.
DROP USER [ IF EXISTS ] <name>
Specifies the identifier for the user to drop. If the identifier contains spaces, special characters, or mixed-case characters, the entire string must be enclosed in double quotes. Identifiers enclosed in double quotes are also case-sensitive.
Dropped users cannot be recovered; they must be recreated.
If you wish to disable a user instead, use ALTER USER and set
DISABLED = TRUE.
DROP USER user1;