There are a variety of ways for one to remove all contacts completely from an iPhone. One of the easiest ways is to download the 'Spring Clean' app. The app will bring up the full contact list and one can select all and delete. Many other processes do not completely clear the contacts.
It shouldn't because all your doing is turning it on and off
Yes there are many Apps out there ex: Find My iPhone and also if you have iCloud account setup you can remotely erase the data from lost/stolen iPhones
Yes, well there are a couple of options, but i think. You should just erase the whole phone.
factory reset it or restore it
No. Replacing the battery will not wipe the phone. Make sure the phone is off before you disconnect the battery though!
the same way with all of the other iphones
Dry erase markers - it can erase off of anything, like Boards, Hands, etc... Wet Erase markers - it will be a little harder for people to take off of anything.
All you have todo is attach the iPhone to your computer insure iTunes is open and then select restore to factory settings options, which will reset the handset and erase ALL previous data.
Actually, It doesnt. 'Cause its the purpose of backing up the data. After the update, Your iphone will restore then it will put back your old data.
erase it :)
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To reset an iPhone model A1387 (iPhone 4S), go to "Settings," then tap "General." Scroll down and select "Reset," then choose "Erase All Content and Settings." Confirm your choice, and the device will begin the reset process. Make sure to back up any important data before proceeding, as this will erase everything on the phone.