I recently bought a pre-pay phone from AT&T - they registered it under my name. i used this phone to contact providers. Now i have second thoughts - if someone track phone numbers registered under my name, they can find this too.
First how to get rid of that phone + its registration  under my name?
Second any suggestion of buying a new phone without showing personal details (not traceable)

Throw it away and don't use it anymore.

Buy a new prepay, and work out your lies prior to going into the store.

Cross your fingers.  I wouldn't work up too much anxiety...the liklihood of you getting tracked down is small and drops with every day you don't use that phone.  Eventually, that number will be registered to someone else, and nobody is going to go thru the work of finding you (particularly if you didn't use your real address) because you called an escort.

Buy a prepaid phone with cash at someplace like Walmart or Target or wherever.

Then go to a library or other public venue to register the phone (that way no IP addresses to trace back to you).  Then, when you buy minutes to add always use cash only.

If you do it right, you leave no tracks.

Agreed with above except that I am super cautious and would not use the Internet to register my phone. I make sure there are absolutely no traces.

I bought a T-mobile phone and always buy refill cards with cash only.

When you go to buy the new phone, have a fake name planned. When I bought my Tmobile phone, they wanted a name and address but they did not require ID so I used the same name I always use for hobbying. This is the same name that I use for my yahoo email account.

This is how I would approach it. Plan to buy with cash only. If the store requires ID, tell them you left it in the car. They may not really care and will put the transaction through. If they do care, go out to the car and don't come back.

I haven't used Boost but I think you can deal with them without using a real name. They are sold at Target stores.

As to the old phone, it is probably best to destroy it. On the very slim chance that LE would ever call it, it's best that you have cut your ties to it. The bigger risk of using your own phone is if your wife ever found it and started her own investigation. So ditch it now.

For the AT&T phone, remove the sim card and destroy the card, then deposit the phone in a stream or other body of water.  If the slim chance of the phone number being tracked happens, You "lost" the phone right after you got it.
    Then go to Walmart, Target, etc. and buy a Tracphone with cash and when activating it give no or fake info. If activating it over a phone, use a payphone.  Buy additional time with cash only.
    Store it in a secure place with the battery removed so there is no chance of it making any noise at an embarrassing time.  Good luck.

I just got a AT&T pre pay. Take the sim card out and destroy it. I had a ATT phone and didn't want to buy another phone so I went into a corp store and they gave me a new sim card for my phone. They asked for my info and I told them John Smith and used the ATT store address, The guy just laughed and showed me how to lode it with more min.

TracFone you can register using a default address in Florida (I'm assuming company offices).  You buy refill minutes with cash & can load them using your phone.  Throw the plastc minutes card in the trash.  

I think taking the battery out is overkill but you do need to be sure it is shut off.  Mine does not come into my home.  

I switch phones in my belt carrier when booking a date & on a date...  

I do not store phone numbers in my hobby phone.  I clean out dialed & recieved calls (Tiger are you listening?)  I do not plan on it being found, but if it is, it will not leave a trail of bread crumbs.  

Clear out "Previous destinations" on your GPS if you use it on a date.  

Worst case scenerio, my tracfone could fall into the street & be driven over by a bus...  & I'd be out $19.95
skb

The reason to take the battery out is so that if the little rascal decides to alert you to a low battery condition.  I don't know if it can when it is turned off, but I'm not taking any chances.