That's the point!
Everything is already OFF.

Except the comparators on old chips, which can be turned off easily with ...
INCLUDE "AllDigital.pbp"
But that also enables all Digital Inputs, so technically everything's not OFF anymore.

Some REALLY OLD 12-bit chips made the T0CKI pin unable to control the TRIS bit while TMR0 was "OFF".
So that's about the extent of the "Turn it all off" header wizard.

; if chip has a 12-bit core
OPTION_REG.5 = 0 ; Free TRISIO.2 bit

But then again, you're really turning something ON (TMR0).

Don't worry about turning things OFF.
Turn stuff ON if you want to use it.