From PostgreSQL wiki
ALTER COLLATION -- change the definition of a collation
ALTER COLLATION name RENAME TO new_name ALTER COLLATION name OWNER TO new_owner ALTER COLLATION name SET SCHEMA new_schema
ALTER COLLATION changes the definition of a collation.
You must own the collation to use ALTER COLLATION. To alter the owner, you must also be a direct or indirect member of the new owning role, and that role must have CREATE privilege on the collation's schema. (These restrictions enforce that altering the owner doesn't do anything you couldn't do by dropping and recreating the collation. However, a superuser can alter ownership of any collation anyway.)
name The name (optionally schema-qualified) of an existing collation.
new_name The new name of the collation.
new_owner The new owner of the collation.
new_schema The new schema for the collation.
To rename the collation de_DE to german:
ALTER COLLATION "de_DE" RENAME TO german; To change the owner of the collation en_US to joe:
ALTER COLLATION "en_US" OWNER TO joe; Compatibility
There is no ALTER COLLATION statement in the SQL standard.