what would be the impact of disable DES and 3DES ciphers on the VIP and what level of testing can be done after Disable

Hello, I recommend you check SSL profile statistics before turning off DES and 3DES. Go to the VS statistics and then choose the SSL profile statistics or use tmsh command:

 show ltm virtual name detail

Check ciphers section:

 Ltm::ClientSSL Profile:Ciphers

If you don't have connections using those ciphers, you can disable without risk.