Recommendations for using a 240V outlet with 120V equipment
Your least expensive option might be to replace the outlet with a 120V outlet, and replace the two-pole breaker at the other end of the wire with a single-pole breaker.

Of course, it might depend on whether you can do it yourself, or convince your landlord to do it him/her self, or whether you are in some institution where you have to fill out piles of paperwork to get it done.



Edit:  A 6-20 outlet does not have a neutral connection, but if there is a neutral wire taped off in the box, and if there's room for more than one outlet in the box, you could have a 120V outlet on each of the two phases, and no need for access to the breaker panel at all.