Deleting the account will delete the account and any synced data from your phone but not from iCloud. Provided you are signing back into the same account and not changing to a different account, you data will be synced back to your phone when you sign back in.
However, photo stream photos are only retained in photo stream for 30 days. After that they are deleted from photo stream but will remain on your phone. If you delete the account, then sign back in, only photos from the last 30 days will be restored to the phone as the rest are no longer in photo stream. If you have photos in photo stream older than 30 days that are not in your camera roll or backed up somewhere else, save them your camera roll before deleting the account. To do this, open the My Photo Stream album on your phone, tap Edit, tap all the photos you want to save, tap Share, tap Save to Camera Roll. You can then delete the account without risking losing your photos.