cannot trash malware NGPlayerSetup.dmg

• Open Terminal
• type cd .Trash followed by Return
• type rm NGPlayer followed by Tab
• the name should now auto-complete
• type Return to remove the file
• reboot

Please be aware that this will just remove the DMG from your system, it will not cleanout any malware which might already have gotten installed.

PC Risk has a page on its removal - How to remove NG Player from Mac?

Ultimately they're trying to sell you their own software, but you can read their guide for free ;-)

You should also invest in a proper, recognised, full-time antivirus suite. Macs are not immune to infection, merely less-likely targets overall.

At minimum, I'd grab the free version of Malwarebytes but ultimately I'd get something that scores well on a recognised test site like AV-TEST