You do not need access privileges to change your own PASSWORD, STARTUP, FALLBACK, or DEFAULT DATABASE definitions. Otherwise, the user submitting a MODIFY request must have the DROP privilege on the user being modified.
For example, although user Marks is not the creator of his own space and does not own himself, he can submit a MODIFY USER request to change his password, modify his startup string, or redirect his default database. Marks can resize finance, as well.
Change the password and other options on user marks.
MODIFY USER marks AS PASSWORD = design, SPOOL = 1500000, STARTUP = 'EXEC paystat;', DEFAULT DATABASE = payroll;