DELETE command - response (1) by M.Saeed Khurram

There is a similar topic where dnoeth has answerd this question. the URL is as follows:
http://forums.teradata.com/forum/database/delete-xxx-rows-with-teradata
You can use this query with the following modification, replace the 10 after sample with .5 and your 50% rows will be deleted! e.g.

delete from tab
where PK_col in
 (select * from (select PK_col from tab sample .5) dt)