The clutch pedal of my Toyota Hilux kzte 2004 does not want to release on its own.

I assume that means that the clutch does not engage/disengage when you press and release the pedal. There are a number of possible issues here. First, does the pedal feel "soft"? Is it easier to press down that usual? If so, the problem may likely be in the hydraulics of the clutch. A bad master or slave cylinder will not allow hydraulic pressure necessary to engage/disengage the clutch.
If the pedal feels normal, then the problem is most likely internal to the clutch mechanism. A bad release bearing or a stripped clutch disc are the most likely culprits for this issue.