For behaviors like platform and 8direction you can set "ignoring input". For MouseKeybord there is no action for disabling it.
But if you add MouseKeyboard to a container with another object that can be destroyed, then the Mousekeyboard can be destroyed, effectively disabling it. To re-enable just create a new MouseKeyboard, but be sure to only make one.
A better solution would be to use a global variable comparison with all your keyboard events:
+ System: Is global variable 'MouseKeyboardaActive' Equal to 1
+ MouseKeyboard: On key Enter pressed