Each wire is already ran and hooked up to lights and outlets it was ran underground with pvc in to the detached garage
This is probably a common issue. The intention is to prevent fire hazards, prevent electricity theft during absence, prevent thieves/burglars using power tools to dismount car parts or invading the main building etc.
An easy, inexpensive and comfortable way can be the installation of a wireless remote (lighting) switch that controls one or more contactors.
These contactors would feed all the electric circuits in the garage. Normally those sets come with 3 switches which can be mounted anywhere. F.e. 1 secret switch hidden in a trash box or under a table in the garage, 2 in the main building.
It might be a help to install an outdoor indicator LED lamp ( permanently on) fed by the garage circuit which is clearly visible from the main building in order to see the status at any time.
Even more comfort and safety can be achieved by installing an adjustable timer (f.e those used for staircases) between the light switch and the contactor(s). No problem, if somebody with memory leakage starts his holiday trip in a hurry, since all electricity in the garage will automatically shut down after 10 min or 2 hours.
If it were me, I would get a disconnect box, similar to this: Disconnect Box -Home Depot-
Note: I am assuming that you have only 1 circuit in your garage.
With this box, I would splice the wires where they enter the garage and insert this device. That way, when in the garage, flipping the disconnect switch would stop all power after the box. Similar to shutting off the breaker in the house, except it would be in the garage. No need to go inside.