This is a feature request.

It would be very useful to be able to enable / disable mechjeb module during flight. When enabled mechjeb windows/menu would show as usual, when disabled all mechjeb windows should disappear and any kind of operation it was performing should halt.
Enable/disable should be accessible using the context menu when right clicking on the AR202 part and also assignable to an action group when building in SPH/VAB

When disabling mechjeb the current open windows should be retained for when re-enabled and when re-enabled the windows should reappear right where they left before disabling mechjeb.

The reason that I'm making this request is because when you use a lot of KSP addons that have windows all over the place and having to close mechjeb windows one by one and then reopen them one by one, is quite tedious and annoying at times. Personally I like to have specific set of mechjeb windows open and have the ability to hide all and show all with a single "action".
Initially I thought I would suggest to hide/show all mechjeb windows using a keyboard shortcut but then I thought it would make more sense to have a enable/disable ability all together.