Required software development,System Administration freelancer for WEBSITE SECURITY ISSUES: MALWARE job

I have 2 websites infected with these types of messages:

I have rescanned your account and still found the infected files. I've included the list of infected files at the end of this email. Please remove the malicious codes/files through the FileManager in the control panel, or through FTP.

During a routine scan, the security team at FatCow
discovered infected files in your "millrivergardensuppl" account.
Typically, these security vulnerabilities are due to the presence of
an outdated application or script in your account.

Can anyone please help this issue?

Skills & Expertise Required

software development System Administration