To leave alone or to neglect; colloquial way of saying to abandon or ignore someone/something.
宿題をほっぽかしてゲームばかりしていると成績が下がるよ。
If you keep neglecting your homework and only play games, your grades will drop.
彼女はペットを一人でほっぽかすことはできないと言った。
She said she couldn't just abandon the pet by itself.
仕事を途中でほっぽかすのは社会人として問題だ。
Abandoning work halfway is a problem as a working member of society.