You do not need to uninstall the previous version of ArcGIS Pro before installing the latest release. However, if you have installed any language packs for the previous version of ArcGIS Pro, it is recommended that you uninstall all ArcGIS Pro language packs before installing ArcGIS Pro. Remember, only one version of ArcGIS Pro can be installed on a machine at a time, so by installing a new version, the old version is overwritten.