Doesn't matter if anyone has a right to suicide (ethically, I mean; legalities are either in line with an ethic you can logically argue for, or they're just the product of sociological norms and have no meaningful normative merit).

The only right anyone has to stop people from committing suicide is making their conditions better so that they don't feel that life isn't worth living anymore. Failing that, preventing the suicide is effectively proactively contributing to prolonging that person's suffering.