DTW update of UDF on OJDT where previous value needs to be deleted

Experts,

I need to update our OPRJ table (which has many UDF's) periodically. In some instances I need to delete the value in the UDF to show a blank/NULL value on my subsequent queries.

I did some research and could not get the '\' or \ to actually clear that field of that value. Is this because it was a UDF? Can I not clear a UDF in this manner?

Any advise will be appreciated,

Marli