Malware problem and Blacklist to remove

Hi My website has some problem.
It is affecting from malware, however i have removed malware but i need security check.
I need that malware do not attack again so we want to solve all security features
It shows security header issue so we need to fix because emails not coming due to this
X-Powered-By PHP/7.3.25; PleskLin The server sent a Powered- By header, this may leak server technology and version information.

We want that header should not send on browser any information of server.
https://webscan.foregenix.com/webscan_results.html?scanid=44c4723d_42d6_4596_8ab0_eea6dcf2f254&type=2&emailaddress=
It shows 3.5 but we need 5

Please discuss with me

Thanks
SUNIL