Yes.
If you click Edit Series... you can delete all of the occurrences in the Recurring Dates tab. However, this will not label the series as OneTime yet. The RecurrenceType field is the field that holds the values OneTime, Series, or Occurrence. You can add a checkbox object and the Recurrence Type field to the Update Selected Work Orders… section of the FieldService_WorkOrderList screen. This is similar to what we did on this forum post for the Sort Order field.
Remember that the RecurrenceType is simply a text field. If you change it to text other than OneTime, Series, or Occurrence then the record might not appear in the default filter views for your Activities grid. Additionally, there is a field in the Activity table called RecurrenceInfo which holds the series information. I would suggest also adding an action in the Update Selected Work Orders button to clear this field when you are changing the recurrence type.
- Jason