Should i trim off the separated nail before applying antifungals to my toenails so it can get to the affected nail bed?

Yes.: If you can trim the loose nail without causing any pain or bleeding, then in general, it is a good idea.

Yes: Most topical anti fungal medications will not penetrate the nail plate. Therefore, cutting as much of the infected nail back to expose the nail bed, will allow topical medication to treat the underlying fungal infection on the nail bed (skin under the nail).