Remove last sentence from string using C#

I have the follwoing string

"Nominated By Anjali Agarwal <br /><br />This is test by Anjali<br /><br />Nominated By Anonymous <br /><br />This is test by anonymous<br /><br />Nominated By Anonymous <br /><br />"

How can I remove the last sentence "Nominated By Anonymous" from the above string.

I only want to remove the last occurance of "Nominated By Anonymous".

I dont want to remove the previous "Nominated By Anonymous" from the string.

Also, Anonymous can be replaced by different words in the string so it can be "Nominated By Anonymous" or "Nominated By Anjali" or "Nominated By" certain name.

any help will be appreciated