Its because the default wallet file is still on your PC. So each time you install Electrum it picks it up.

You can either delete it, check in User/AppData/Roaming/Electrum/wallets or you can just create a new wallet from the file menu.

Just make sure that you have no coins on the wallet you are deleting and also make sure that you have a backup of that wallet even if you do not plan on using it again, you never know and never is a long time.