Not being familiar with PG Bison I had to Google it and it appears to be melamine-faced board or one kind or another:
MelaWood® is PG Bison's leading brand of decorative melamine faced board (MFB)....
MelaWood® uses either BisonBord® or SupaWood® as a core....
There's a chance the hold of the glue to the edges of the legs is fairly weak (because glues don't bond well to melamine) in which case all you really have to overcome is the glue hold between the biscuits and the core material, BisonBord being chipboard/particleboard and SupaWood being MDF.
To be honest the glue hold on biscuits even in solid wood is rather famously not great! It will typically be much weaker in either chipboard or MDF because they're friable materials and tend to over-absorb glue.
Quite apart from this you'll be doing any investigatory prying/levering on what is now and what will again be the underside of the desktop, so I don't think you're risking much if the separation isn't quite as neat as you'd like. Any ugliness that results will never be visible unless someone crawls under the desk and looks up.
But if it looks like it is putting up a lot of resistance it would not hurt to heat the joint line very well using a hairdryer, or more cautiously with a heat gun. The glues most likely to have been used here are both softened by heat.