I disposed off many of my clothes during the seasonal wardrobe change which I didn't wear anymore.
I threw off many of my clothes during the seasonal wardrobe change which I had stopped wearing.
ご質問ありがとうございます。
意味：
衣替え：seasonal change of clothing; change of wardrobe (季節が変わると、服の質も変わってくるので、冬や夏の変わり目に衣装を変えること）
着なくなった：which I no longer wear.
捨てました：disposed off, threw away
例：
- Seasonal wardrobe change is best time for cleaning.
衣替えの時が一番掃除になります。
- Storing clothes and accessories away for the season is a good way to make things last longer.
オフシーズンの衣類やアクセサリーは 、 衣替え の時きまでしまっておくほうが長持ちします。
お役に立てば嬉しいです。
日本 
インド 
