Danke, Kai!

I don't often disagree with Kai, but if you use 'really,' you need to change the position of the adverb in order to communicate the meaning you intend.

I really didn't want to = I very much didn't want to (= strongly negative)
I didn't really want to = I didn't want to very much (= mildly negative)

You could also just say

At first I didn't want to ..., but ...
I didn't actually want to ... at first, but ...

And actually, if you include 'any more,' it would probably be better just to rephrase. 'Originally' is certainly also a possibility.

My original thought / idea was to give up singing the role, but ...
I had originally intended to take the role out of my repertoire, but ...

Or just the past progressive, with a negative:

I actually wasn't planning to keep singing the role, but ...

OT: Manrico, das geht aber nicht gut aus mit der Rolle! Mach es wie Placido Domingo, sattle um auf Bariton, die werden nicht oft schnell abgemurkst!