How do you set a registration form email link to open the link in the original browser tab?

I set up a registration system which requires clicking on a link in email to confirm/activate the account. It looks like:

$textContent .= "Dear John,\n\n
Thank you for registering with YourBusinessName. 
To complete registration click on the activation link:
\n\n
<a href='https://www.your-website.abc/activate-account' target='_blank'>activate</a>";

This works however when you click on the email link it always opens in a new browser tab (or window depending on preferences). This leaves a confusing extra, lame, window in a tab.

How do you make it either open in the original tab/window or perhaps open while simultaneously killing the original tab?