how do i get rid of tapesnake virus

Any popup message indicating you have a virus will always be a scam. Do not respond.

Force quit Safari, then restart Safari while holding the shift key.

Force quit Safari using the Command + Option + Esc keyboard shortcut.

Then relaunch Safari while holding down the Shift key then download and run Malwarebyyes Anti-Malware for Mac formerly known as AdwareMedic. It's free.

If you would rather not download Malwarebytes Anti-Malware, you can remove the malware manually following the instructions here > Remove unwanted adware that displays pop-up ads and graphics on your Mac - Apple Support

See some threads

Tapsnake virus detected on my MAC...recommened to download Mackeeper to remove virus..is this software legit?

You are welcome.