I just downloaded Electrum and when it asked me what kind of wallet I wanted, I accidentally pressed the kind where I need two machines to use it. I didn't understand that this was the kind of wallet I chose until after I entered the seed.
There is no discernible way to cancel this action and get back to the original screen that asked me what kind of wallet I wanted. There is a cancel button. This quits Electrum, and when I reopen it, I am back on the same page. There are no top menu options. I reinstalled Electrum twice and it still reopens to this screen.
You most probably created a multisig wallet.
If you're on Windows, go to Users\%UserName%\AppData\Roaming\Local\Electrum
On linux, go to your Home folder, press Ctrl+H, you'll see .electrum folder
Inside you'll see wallets folder, go in it, you'll see a file "default_wallet", rename it to "OLD_default_wallet" or anything else (in-case you need it in future).
Reopen electrum and this time you'll see the original screen and you can make another wallet. This time just choose a "standard wallet" and make sure to write down the seed carefully somewhere safe.
Note: If you are expecting a payment in your old wallet then make sure to keep back up and note down the seed of the previous wallet before you do the steps above.