Hi Markus,
Thanks for contacting Syncfusion support.
At present we do not have support to “Erase the free hand drawings” in WPF PDF viewer. We have logged a feature request for this and at the planning stage for every release cycle, we review all open features and identify features for implementation based on specific parameters including product vision, technological feasibility, and customer interest.
Based on our present commitments, this feature is expected to be implemented in our 2020 Volume 4 main release. We will let you know when this feature is implemented. You can track the status of the implementation from below link,
Disclaimer: The date for the feature implementation is tentative and not a commitment on our parts.
Regards,
Uthandaraja S