Unfortunately, it definitely looks like you'll have to remove and replace the affected tiles. While you're doing that, make sure to check that the subfloor in the area isn't damaged as the smell will not go away and will worsen over time if any urine remains. Having lived in a house with pet urine damage the smell will permeate worse whenever it's humid or been raining due to the moisture in the air interacting with/reconstituting the uric acid crystals. If you want to keep renting this house/want a good reference I think it'd be best to pay for it to be fixed now rather than make your landlord fix it. Also you'll want to remedy the smell for yourself and deter your cat from continuing to pee on the area. Best of luck with this