How to delete synced photos off of iphone? - 1

How do i remove synced photos off of an iphone? Preferably without having to connect the iphone to a computer then itunes because it's my friend s phone and my laptop, but we arent seeing each other for a few months because I ll be away and we don't have an iphone cord that spans kilometers lmao. All solutions are welcome!

Would this be good for YouTubing?

I wanna start a channel on YouTube of me cycling around. I only have my iPhone 6 for recording so I'm going to get a chest mount for it and wear it when I'm cycling, I planned on just shooting a video of me cycling and then throwing some music on it and putting it on YouTube. Does this sound like a good idea to get into youtubing as a hobby?

How to prevent any damage after an iPhone gets wet?

I accidentally drop my iPhone 5s in the sink and I dried it and I put it in a bag with rice on it and now it does work but the only problem I have now is when I turn it off, it does have battery but it won't turn on and I can only turn it on by charging it. What can I do to fix this problem?