Cannot Install; Need Alternative For Virus Scanners

I'm trying to find a way to run scanners on a computer where the Administrator account is locked down. Right now, I'm able to log into the other accounts which aren't Admins, but I still need to find a way to perform scans and get any malware off the system since I won't be able to install the tools I would normally use. Any and all help or suggestions are genuinely appreciated.

 

I'm in a non-Admin account meaning it asks for me to sign in as the Administrator which I cannot do. This is either due to the password being changed accidentally (children might have done this) or a previous malware infection may have compromised it. So, I cannot install software since I cannot enter the current password, but still need to get anything malicious off the system. Is there any online based service that can help me do this?