There is one of these second hand clothes collection boxes next to Shi-Da University sports field, off Heping East Road. The box is located on Roosevelt Road Sec 2 Lane 81 but it is a one-way street, and the entrance to Lane 81 is actually on Heping East Road, not Roosevelt Road, between a National Health medical clinic and the Shi-Da Sports field. It is less than 25 meters down Lane 81, you should see it on the left side of the lane.
I am also looking to get rid of some clothes, but they are quite nice and was looking for a second hand store, or a Salvation Army-type of shop. I am trying to donate the stuff, it's too nice to dump in a clothing bin or throw away.
Please let me know if there is any such store.