I resigned from my job due to better opportunities. My employer has canceled my work permit but not the visa. They have told me to cancel the visa myself because i did not have my passport on the day we were to cancel everything.

1. Will my visa remain valid until it expires in 2008 if i choose not to cancel it?
   
2. Do i need to produce my work permit when i go to immigration to get an extension of stay every 3 months?
   
3. Is there any unforeseen problems with this process such as renewal?
   

Thankyou

From the fact that you do not obtain an extension of stay from Immigration every three months it appears you were on a one year extension of stay and making address reports every three months. If that is the case your extension of stay is now invalid and you have/had seven days from end of employment to depart Thailand. If you do not do so you will be on overstay.

On the other hand - if you had a multi entry visa issued by a Consulate and were making 90 day exits to another country and then returning for a new 90 day stay the loss of employment would not invalidate the visa or your current 90 day stay.