-Ammonia is 0, Nitrites are +0.3/ppm (at the moment), Nitrates are at a safe level
Toxic..

-Tank is Pentametical 60L (14us G)
Fine for a single frog.

-Substrate is small-large gravel from a petshop
Run the risk of the frog ingesting and becoming impacted by this substrate.

-Two filters, on lowest setting; one is a stingray, the other is a fluvial. I will remove the stingray once cycling has stopped.
Cycling doesn't stop really, that's the point of the cycle. Ammonia to Nitrite to Nitrate and then controlled via partial water changes.

-Nitrogen Cycle is almost complete, Ammonia is being converted into Nitrites and they are lowering and turning slowly into Nitrates
Correct, though the cycling should have been complete before adding livestock.

-Plants are live, Elodea Canadiensis
-Lots of hiding places (not sharp, of course)
-Temperature is constantly 20'c
Good.

-Fed frozen bloodworms and very small Repotmin pellets
-Water changes every week, 20%
This is fine, though I'd feed more reptomin and offer the bloodworms more as a treat if at all (known to cause bloating disease).

For two weeks, I've had them in with three goldfish, who were finally put into my pond so now they're on their own in the tank.
The goldfish had no business being in this tank; way too small for all these species. So good move there.

Now, info about my frogs:

Two African Clawed Frogs (Xenopus Laevis), anywhere from two weeks to a month old, they're about 1inch in size. Sex is unknown at this moment in time.
No way to know for quite some time. Two adult frogs will outgrow this system.

Now, I think that is all the information needed for the following question:

Is it normal for them to 'hover' near the top of the tank?
Yes but not all the time. They do enjoy to bask, rest at the water surface.

I've been studying them for a few hours a day, when I first got them, they were always hiding and only came out at night and when I fed them (as expected). But ever since I've removed my fish they seem a lot more active and playful, but I've also noticed is that they're always near the top of the water instead of being at the bottom, why is this?
Xenopus are nocturnal by nature, though in captivity do become active during all hours of the day. My frogs seem to rest at night. Being small juveniles housed with fish can be scary, they could see them as potential predators.. no scary fish = a better feeling of security for the frogs. Xenopus are predators but also a prey species, they are usually quite aware of predators or what they conceive to be predators.

If I had to run the numbers on how my frogs act I would say they spend 80% of the time on the bottom and 20% on the top. If you notice your frogs having trouble swimming or any other unusual behavior I would attribute it to the fact the tank is not fully cycled. I would dose with Prime and do frequent water changes in the future try to do a fishless (or in this case, frogless) cycle, you can google this for more info.

Thanks for any help.
Hope this helps.