After upgrading to 15.4.1, the PMO accelerator was installed, including the views by accident. This overwrote our custom views. Is there a way to back out the PMO views and restore our custom views that were overwritten?
Unfortunately no, there is no way to back out the PMO accelerator views once they are installed. The only way to get the custom views back is to roll the system back to before the upgrade and then run through the upgrade again. When installing the PMO accelerator, do not install the views. As noted in the documentation, it will overwrite any custom views that are in place.