This information is for TaskPaper 2 which is old and outdated.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 all tasks in the current project tagged with @done.
tell application "TaskPaper"
tell front document
set p to containing project of selected entry
set done_entry_ids to {}
repeat with each in entries of p
if exists (tag named "done" of each) then
set done_entry_ids to done_entry_ids & id of each
end if
end repeat
repeat with each in done_entry_ids
delete entry id each of p
end repeat
end tell
end tell