Do i need to leave the us to change from one tn visa to another tn visa?

You can either file an amended petition with CIS or go the border and be readmitted. If you are from Mexico you probably also need a new visa, so filing an amended petition will be better. .

You can go to the border and be readmitted or you can file an amended petition which is probably the most common option.

If a Canadian citizen, you can go straight to the border and have your employer file a new TN petition on your behalf. New employer could also petition you with USCIS. Takes months, however. If a Mexican citizen, best to have new employer petition you with USCIS, otherwise will need to exit and apply for the TN visa again at the US consulate.

My colleagues make a great point ... it depends on your country of citizenship. Also, the company should be using an immigration lawyer. I don't doubt that you may be a great management consultant ... don't try to be an immigration consultant also.

You have received an offer with another restaurant and if the offer is from another employer then a FORM I-129TN can be filed with USCIS by the new employer. If you are Canadian you can visit one of 13 U.S. port of entry to obtain the TN. If you are from MEXICO , you can visit the U.S. consulate in Mexico.