Co-signers rights

my boyfriend co-signed on 40 acres several years ago with the woman he lived with in Kansas. Then again on a second on the same property. They are no longer together, she lives in another state. He knows the only way to get his name off this is to have it re-financed.
She currently has the property under a 'land' contract where the current tenants paid her a lump sum of $3000, took over payments, then in a year will re-finance. --If they qualify.
He did not receive any of this money and is not using the propery on his income taxes.
He actually found out obout this by mistake. Can she do this without his knowledge or sell the property without his knowing?
Thanks

[HomeGuru]

Yes provided his name is not on title to the property.

He said his name is on the title. A few weeks ago she called and asked him to sign some kind of deed thing to relese him. Although his name would still be on the note.

[HomeGuru]

Tell him not to sign anything without first having an attorney review it. Sounds like he's clueless in Kansas.