Failing Log Shipping recovery doubts

Hi
If there is an unusual situation, this is the one.
I had very well working Log Shipping on a DB that was not in use(remain unused). One day(year ago) someone has rebuild the secondary SQL server without canceling the Log Shipping first. Today i have problem with enormous MSDB because of errorr logs from the broken Log Shipping.
My doubt is what to do: 1. to rebuild the primary SQL server instance OR 2. to try to delete LS settings and clean up the MSDB ?
additional information(Primary SQL server is not in use, no valuable data on it, all backups done and secure, 1 week to have good SQL server)
I am kindly asking for your opinion. Regards

It is probably quicker and easier to clean up the LS history. Read up on this stored proc:
sp_cleanup_log_shipping_history