Is there a way to reset the service engine soon light on a 1999 silverado without it code scanner?

Have you diagnosed and repaired to cause of the light coming on first?
If not, turning the light off only masks the problem.

truck was running rough put some injector cleaner and octane bost i it and it fixed the rough part but then light came on i believe it was because of trash in injector that caused prob it has happened before

The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.