Uninstall the drivers before removing the 6600, use https://www.amd.com/en/support/kb/faq/gpu-601
To make it easier for installing the 7600 drivers after the swap, download and save the driver package direct from AMD before doing the above.
My PC- Ryzen 5 5600x, B550 aorus pro ac, Hyper 212 black, 2 x 16gb F4-3600c16dgtzn kit, NM790 2TB, Nitro+RX6900XT, RM850, Win.10 Pro., LC27G55T.