Quickest was to disable engines/lock throttle at 0%?

[THX1138]

Is there a quicker way than right clicking on each engine?

[zekes]

Hitting X, or right clicking and hitting disable.

[Mastikator]

If you want to only shut off individual engines then you could use action groups. So pressing "1" toggles one engine and "2" toggles another.

[jarmund]

If you want to only shut off individual engines then you could use action groups. So pressing "1" toggles one engine and "2" toggles another.

This. In career mode, once you have unlocked custom action groups, you should use action groups for this, by assigning "toggle engine" to a group. If you only have basic action groups unlocked, you could use one of the basic ones. I rarely use the abort group, so If I really need to, I use this for stuff, as it's conveniently bound to backspace.

If your craft is already flying, you would need this mod as it allows you to edit action groups post-launch.