tectite fitting on my shower

[ianmcd]

As @dilalio says keep the white plastic part of the old shower and you will see where that section disconnects, it is usually very easy, and just leave that section and attach it to the new shower if they are exactly the same

 

[Madrab]

That looks like a tec sprint street elbow into a JG speedfit. So it all comes down to how much of that hole/pipe does the shower cover when its on the wall and the case is on. Can you cut enough of the tile away - left into the centre of where the shower case will be - to get to the fitting with pair of long nosed vice grips, enough to loosen the fitting then remove the elbow. Once the shower's back on the wall it'll cover any access hole you've had to make.