Many a times we send invitations to people whom we do not intent to send. This can happen when you upload your address book to LinkedIn. So, if you found out that you sent an invite accidentally you can act quickly and revoke the invitation. For this,
Open your linkedIn app.
Go to the LinkedIn Inbox.
Then click on Sent for you to see the invitations that you have sent.
Check whether the invitation that you have sent has been accepted or not.
If it is not accepted then click on the subject line of the message and click Withdraw.