You really don't need a professional. You have what appears to be a "shark bite cap" on the end of that pipe. If you go to the orange big box store, you can buy a tool to remove that shark bite cap for about $1. It looks like an orange horseshoe. You would put it on the white pipe and slide it towards the cap, and the cap will come right off.
I am not sure why the cap was installed. The purpose of that temperature and pressure relief valve (T&P valve) is to open and allow water to get out if the temperature or the pressure of the water in the tank gets too high. When it opens, it relieves the excess pressure. In normal operation, it should never open. There would normally be a pipe screwed into that T&P valve that would terminate within about 6 inches of the floor. The orange big box also sells those made out of pocket for a couple of dollars.