Hi
I dont think we have an option here. There was an enhancement request for it and its its in a Terminated Status now. And there is no future plans to fix this. Please see this CSCue54013.
Symptom:
Sent/received data by File transfer and Screen capture features is saved in "C:\Users\username\Documents\MyJabberFiles" on desktop. Client does not remove or limit the growth of the contents in this folder.
Conditions:
File transfer and Screen capture feature is used regularly.
Workaround:
Manually delete the files