No legitimate big company like Microsoft or Telstra will EVER...

No legitimate big company like Microsoft or Telstra will EVER call you about a 'problem' with your PC, if there is a problem with it YOU will be the first to know and not some guy in India, hang up the phone immediately and NEVER NEVER NEVER give any unknown person access to your PC.  If you initiate contact with a legitimate company then it's probably OK to do so.  I remote service lots of people with teamviewer but they know me.

Ultimate4trading looks l more like a binary trading scam than anything malicious, simply remove it using the windows uninstaller from the control panel.  If you're still worried, use malwarebytes free as mentioned by someone else.

https://www.malwarebytes.org/antimalware/

Choose the free version (on the left) and not when installing it to uncheck the google toolbar options and homepage options (If they are there, I might be getting mixed up with another program. )  Also UNCHECK the 'install free 30 day trial' box as well otherwise you'll get bugged for payment after 30 days.