need to reset.

Hi espinoza134,

If I understand your question correctly, you purchased a Mac from a third-party seller and it wasn't erased correctly. Unfortunately, this might be difficult to resolve.

Do any of these lock screens appear on your Mac? If yes, which one(s)?

If none of those screens appear, you might be able to erase the Mac and start over. Follow these steps: How To Fully Erase A Mac Using Recovery A… - Apple Community

WARNING: If your Mac has the T2 Security Chip or an Apple silicon chip (M1 and later), these steps could potentially brick your Mac if Activation Lock is enabled. The previous owner's Apple ID and password might be required. If they cannot remove Activation Lock, your only remedy or remaining option is to either get a refund for the Mac or contact Apple with proof of purchase containing the serial number.

If the original owner do not properly prepare it for resale,

see > What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

Then you need to contact the original owner to properly clear the iMac or ask for a refund and send it back.