incompetent

someone who is not competent to take effective action

legally not qualified or sufficient; "a wife is usually considered unqualified to testify against her husband"; "incompetent witnesses"

not qualified or suited for a purpose; "an incompetent secret service"; "the filming was hopeless incompetent"

showing lack of skill or aptitude; "a bungling workman"; "did a clumsy job"; "his fumbling attempt to put up a shelf"

not doing a good job; "incompetent at chess"

not meeting requirements; "unequal to the demands put upon him"