If you are not completely sure you made an individual customization to your HR solution which you want to keep, we recommend you remove layers to be sure you can always benefit from all features of the newest solution update.
In case you need to remove layers, this page shows you how it works.
This guide shows you how to do so in bulk using the external program XrmToolBox. It is possible to remove layers without the XrmToolBox (Guide), but then you have to do it one by one. We highly recommend using XrmToolBox, since removing the layers in bulk is much faster and easier.