This information is for TaskPaper 2 which is old and outdated. TaskPaper 3 is the current version of TaskPaper. For TaskPaper 3 support please visit the support forums.
This script deletes the selected task if it is tagged with @done.
tell application "TaskPaper"
tell front document
set selected_entries to get selected entries
repeat with each in selected_entries
if (exists tag named "done" of each) then
delete each
end if
end repeat
end tell
end tell