I have two questions:
It might depend on the particular bike rack but yes generally you can remove them by just taking out the pin that goes through the receiver. You will want to use a locking pin for that reason. Some of them also fold down or fold out so you can more easily access the rear gate of an SUV or Truck
I have one for a 2 inch receiver that supports up to 4 bikes hanging from arms...think it is a Hollywood brand. It folds down. It is steel and quite heavy but for me provided a good price/feature trade off.
I suspect the ones that support the bikes by the wheels on rails are kinder to the bikes but they seem to be quite a bit more expensive.
Hey there @TheYuens!
I see that one of our users @OldGuyot was able to answer the first part of your question. Removal is not a difficult task with hitch racks! To answer the second part of the question, i'll link you to a previous conversation where @REI-JohnJ gave some great advice on hitch carriers for heavier bikes.
Before you settle on a rack, be sure to know what size hitch receiver you have. Some racks are offered in 1.25" or 2". However, some racks are only available in one or the other.
Hope this information helps!