when they cancel my visa

Of what i understood is you are moving on in your career. I dont really know why they are asking to cancel your visa. All they need to do is allow mobility which can be done online. And then your new company can transfer your visa onto their company. I have never experienced it first hand nor will i so someone else might provide a more in depth analysis. 

Thank you for you response... I am also confuse or maybe they are just asking just to be sure that my current company will release so that they will not waste the visa they for me? and about visa cancellation when i give my resigantion the same day they will cancel my visa?? thank you

There will definitely be a notice period for one month or above according to your contract with your old company which you will have to serve before you can leave and they will cancel the visa after you are finally out of the company. What I will recommend you is to ask your old company to 'allow mobility' which can also be done online by your employer and then your new company can apply in LMRA to transfer your visa onto them. If they cancel your visa and your new company applies for a new one the process tends to get comprehensive.

As I said earlier I am not an expert in this area so better get some advice from someone else as well. You can ask the HR of your previous company or contact LMRA call center 17506055 directly also if you have any further queries.

thank you... by the way im transferring to other country.. right now im in bahrain and my new employer is in uae(abu dhabi).. just for clarification i am not transferring to another employer within bahrain but with another country.

There is no standard policy on this. The best people to answer this question will be the HR of your current employer. Each company has different policies so just check with them.

Some companies cancel the visa immediately, some do it after the effective date of resignation (after the notice period) and some give time for you to find another job and settle down.

If you are moving to another country, cancellation of your visa should not matter to your new employers. As long as you agree a start date with them and turn up by that date they should be fine.

Thank you guys for helping me out... management told me that they will cancel my visa after my 30 days notice.. Is it possible to cancel my visa before my 30 days notice expire I'd like to ask them to cancel it two weeks before my 30 days notice and by the way what documents do i need to ask to them? (release paper, cancellation notice or whatsoever) do you guys have any idea...

Any Idea will be greatly appreciated...

You can request an earlier cancellation and if the company does not mind, they may do it for you.

There only document/proof you can get is the cancellation stamp on your current visa and another new stamp on your passport that permits you to be in Bahrain for 30 days from the date of cancellation.