Reverting Back to Built-In Render Pipeline
This feature is only available from JMRSDK 4.24.1 onwards
Remove the BlitMaterialFetch script from the Left & Right cameras which can be found under in JMRMixedReality prefab.
Delete the JMRSDK_URP_Extension folder.
From the package manager remove the UniversalRP package.
Re-Import the JMRSDK packages. This will revert the materials in JMRSDK which got converted to Universal Render Pipeline/Lit back to the built-in standard shader. Unity does not provide a converter to revert materials from URP to Built-In.