how remove other memory

Not possible to remove "Other" entirely, but 631.3MB is too large. The size of "Other" on my iPhone is less than half the size of yours.

Try restoring your iPhone with iTunes from your iPhone's backup.

Which firmware version are you running?

If you have installed the current firmware version and you haven't deleted the download from your computer, you shouldn't have to download the firmware update again - it should remain on your computer.

Other is memory used by apps and system metadata. This may or may not be a reasonable size depending on how many apps you have and how much memory they require for data. The only way to try to reduce it is to restore.

You have been provided the answer. The answer is not going to change if it is not what you wanted to hear or if you don't like the answer.

You can try whatever you like.

From Allans' very first answer to your question:

"Try restoring your iPhone with iTunes from your iPhone's backup. "

If you restore it will first check to see if there is a later version. If there is it will download that version and install it. You cannot restore from a backup, as the backup does not contain the firmware. The firmware is a separate file of type .ipsw.

I wouldn't bother, though; 600 MB is a little large, but restoring might not reduce it if it is all app data, and even if it is reduced it is unlikely to save more than 300 MB.

That sounds right. I doubt there is any more memory to be had.

have you cleared the cache(s) in your applications?

My "other" memory shows 4.76 GB. I understand that restoring from the itunes reduce the size but will I lose some information ?

iTunes maintains a backup for your iPhone, which is updated as the first step during the iTunes sync process. This link provides the data that is included with your iPhone's backup.

http://support.apple.com/kb/HT1766

Although contacts are included with your iPhone's backup, contacts are designed to be synced with a supported application on your computer.

Although photos in your iPhone's Camera Roll are also included with your iPhone's backup, photos in your iPhone's Camera Roll should be imported by your computer as with any other digital camera.

iTunes content including 3rd party apps and any photos transferred from your computer are not included with your iPhone's backup. All iTunes content including 3rd party apps should be in your iTunes library on your computer, and any photos transferred from your computer should remain on your computer.

Before restoring your iPhone with iTunes from your iPhone's backup, import any photos from your iPhone's Camera Roll that haven't been imported. Follow this by syncing your iPhone with iTunes to update your iPhone's backup along with any data kept synchronized with a supported application on your computer such as contacts and calendar events.