Sorry to hear about the trouble there with VyprVPN on your Mac running Mojave.
Please try the following steps to stop the app:
1. Quit the VyprVPN application from the 'Quit' option in the VyprVPN menu at the top of your screen.
2. To remove the service, use Command+Tab and select Finder, then press Command + Shift + G to bring up the Go To window and type in:
3. /Library/PrivilegedHelperTools A window should open showing the VyprVPNService sitting there. Drag it to trash.
4. Then you will need to log out of OS X and log back in to complete service removal.
5. Empty the trash bin.
6. Restart VyprVPN to prompt the reinstallation of the VyprVPNService.
As to the connection issue, there is possibly a blocked system extension preventing a connection.
If you do not see a system extension approval when launching the app, do you recall allowing it before? If not, then please quit the app and re-open it to see if it shows up.
If there is no prompt, please check for it using the following steps:
A. Access the OS's Security & Privacy settings.
B. On the General Tab under the "Allow apps downloaded from:".
C. You will see "System software from developer "Golden Frog" was blocked from loading".
D. Click Allow, restart the app and try connecting again.
If there is no extension listed in step C then this was either already approved or it was not blocked.
Should the steps above not resolve the issue, please click on the Help menu for VyprVPN, and select Contact Support to send our support department the logs from the Mac and they can assist further.
Thank you for contacting us!