Is it recommended factory reset when new driver installing?
Depends if you are having issues with your current AMD Driver, I would set it to Factory Default before updating to make sure that any GPU modifications you have done doesn't interfere with the new AMD Driver.
I imagine most Users don't set their GPU cards to Factory Default when updating their AMD drivers but, in my opinion, it is a good recommendation.
That way you can tell if the latest AMD Driver is having problems it isn't due to you modifying your GPU Card.
Im asking because prior versions of updates is in my drive. They accumulate and fill the memory.
Also i dont have any issues with my drivers
When I update either my AMD or Nvidia drivers I always delete the AMD Installation folder at C:\AMD.
This folder is only needed when installing the AMD driver plus it may cause any future updates to be corrupted since it has different AMD drivers in that folder from previous AMD installations.
This is generally the method I use and recommend to other Users when updating to the latest AMD Driver:
Use DDU in Safe Mode (Best Method) or from the Windows Desktop with the Internet disconnected but before using DDU delete the AMD previous installation folder at C:\AMD. Then run DDU.
Once it reboots back into Windows Desktop then install the AMD driver. if successful than reconnect the Internet and again delete the AMD Installation folder at C:\AMD.
That folder can grow into several Gigabytes large after several AMD Driver updates.