Hello PChatman,
Solution 1:
Fallow settings> general> iPhone storage and find the app you want to delete. Click it and then;
if you want to delete it temporarily click offload app. ( It will offload the app but your data will be remained and it is gonna continue taking space in your storage)
if you want to delete it permanently click delete app. (It will delete it all of your data with the app you deleted.)
Solution 2:
If you still can not delete it try restarting your phone, it will fresh up your phone. Then try again deleting the app you want to delete. Hope that it helped, have a nice day!