今天我可以不写作业，反正明天也没有课。 你走吧，反正我不会留你的。

反正 means anyway

I'll offer you some of my opinions. 反正sometimes means whatever, your example, if translated in English, that will be"Whatever happens, don't tell him". 反正has three meanings: 1. showing the speaker's attitude toward something. For example: 修路反正是好事or 帮人反正没错. it makes your tone stronger. 2. conclude the previous conditon, kind of like "in conclusion". For eample: 不管发生了什么，反正别告诉他。This is your exmple exactly. These two fuctions should be enough. Hope you have fun in leaning.

就當成anyway來用也行