A pressure-quench technique at chosen pressures and temperatures to lock in the highpressure- induced superconducting or non-superconducting phases in high-temperature superconductors (HTS) and room-temperature superconductors (RTS) at ambient without pressures, removing the formidable obstacle to the ubiquitous practical application of HTS and RTS.A pressure-quench technique at chosen pressures and temperatures to lock in the high pressure- induced superconducting or non-superconducting phases in high-temperature superconductors (HTS) and room-temperature superconductors (RTS) at ambient without pressures, removing the formidable obstacle to the ubiquitous practical application of HTS and RTS.