Brackets For Temporarily Connecting Wooden Frames Together?
Loose pin hinge has a removable pin so the hinge halves can be separated. Examples

https://shopmtn.eu/products/scenery-fixings-loose-pin-hinge
http://www.doughty-engineering.co.uk/cgi-bin/trolleyed_public.cgi?action=showprod_T61700

and

https://www.ironmongerydirect.co.uk/product/loose-pin-steel-hinge-100x67mm-brass-plated-pair-546135