Not able to cancel replying

Hey guys I have an issue, when clicking reply to a thread the reply window opens. Lets say I clicked reply button accidentally now I don't want to reply this thread but I am not able get out of the window even if I do when replying another post in same thread I'm replying both this one and the one that got clicked accidentally before. Can you get my issue ?

Yes, I understand, and many seem unaware of this problem and its solution also, which is:

Look at the icons above the message box. See the second last one on the right hand side?

That is where you can save or delete drafts. A draft is: a preliminary version of a piece of writing.

If you select delete draft, I would give it a few seconds to complete the action before navigating away from the thread.

A second option is to simply manually delete it the next time you respond in the same thread.

It will never show up again after that

If this does happen for some reason (like forgetting to delete using the delete draft option),
once you have posted your message and see something you do not want there, like part
of a previous post you no longer desire to respond to, you can edit the post to delete
the unwanted material. Please keep in mind: the edit window is open for only 5 minutes.

I Am sorry but which one in these ?

btw I know the delete button after posting

Your image does not show the second one from the far right...

Hmmm, that's ok I'll post and delete it next time. May be it won't show up in mobile

She's on desktop. You're on mobile. That button isn't on mobile (for whatever reason).
My suggestion doesn't require it.

It's available on desktop mode in chrome.