A typical general answer would be this,
If the clip has an eye on each end of it then use some circlip pliers or 2 screw drivers,
If its just cut ends then use 2 screwdrivers, use one to pry and the other to hold, if you can jam one in the back of the keyway to stop the clip tuning then it will be easier but dont damage the keyway,
You need to expand the sprung clip and pry it off basically and it depends on what tools you have to hand on how well you achieve this,
Some find some small long nose pliers useful and instead of squeezing with them pull them appart to open the clip,
Dont quote me on this but you may find some posts on this if you take a look for 'Tail piece retaining clip' as thats what its called
Tell us the make and model of the lock and even better show us a picture for more info,