Remove copy_back from Python bindings and mj_copyBack from the C API.

PiperOrigin-RevId: 687377331
Change-Id: I355493d92857418b08b5aa90ea38cebe5c475314

src/user/user_api.cc

@@ -75,14 +75,6 @@ mjSpec* mj_copySpec(const mjSpec* s) {
 
 
 
-// copy back model
-void mj_copyBack(mjSpec* s, const mjModel* m) {
-  mjCModel* modelC = static_cast<mjCModel*>(s->element);
-  modelC->CopyBack(m);
-}
-
-
-
 // compile model
 mjModel* mj_compile(mjSpec* s, const mjVFS* vfs) {
   mjCModel* modelC = static_cast<mjCModel*>(s->element);

src/user/user_api.h

@@ -54,9 +54,6 @@ MJAPI const char* mjs_getError(mjSpec* s);
 // Return 1 if compiler error is a warning.
 MJAPI int mjs_isWarning(mjSpec* s);
 
-// Copy model fields back into spec.
-MJAPI void mj_copyBack(mjSpec* s, const mjModel* m);
-
 // Delete spec.
 MJAPI void mj_deleteSpec(mjSpec* s);