What is a good strategy for removing 3d prints from an UNheated Glass bed?
Because you will be printing on unheated glass, you will be using some form of adhesive material. If you use an off-the-shelf glue stick, you will likely find it is water soluble. If the bed is removable, immersing it in warm water for a relaxing soak will provide easier model removal. 

I don't have experience with various tapes, so will avoid recommendations regarding masking tapes or similar material.

Thermal cycling will also provide release. Not a heat gun, as that will break the glass, but a hair dryer applied to the underside near the model, then cooling. Repeat until it releases.

I have used the Fleks3D print plate on my Flux Delta printer in the past, and it releases "like magic" but I don't think they make monster sheets of your printer size. I had also purchased a pair of 20" square Fleks3D plates for a similarly sized printer that never materialized. I'd be happy to sell you the pair, but I think they are too small for your full plate.

It has been said that one can use sand-blasted acrylic, which I believe is the construction of the aforementioned Fleks3D plates. If you have access to 1/8" or 3mm acrylic and can apply a uniform blast of abrasive, you may be able to construct your own easy-release build plate.

It is practical to consider to use a raft for your large builds. Rafts are useful for small items, to provide a greater bonding surface and avoid release, but it also provides a "wedging" location for your release tool. You can more easily slice away the middle of the raft and deal with a thinner layer after the model is completely freed.

EDIT ADD: If the bed is not removable, one can build a dam around the model with clay to hold the water for dissolving the glue.