Can't destroy blocks

Hello! On my island I can't destroy certain blocks that are part of my island. They are quite far away from the spawn point. One of my friends who used to play put them there, but he got banned or something.
Any ideas on how I could fix this?

 

You cannot destroy or place blocks more than 49 blocks away from bedrock.

Is this why?

 

I can come in-game to break them for you if you fill out this format:

1. IGN:
2. Is your island unlocked or locked?
3. Is this because you can't reach them, or can you literally not get to them because they're no longer yours?

 

This could be why, but my friend put them their first, so I don't know how he did it.

 

Thanks for your time.
If it takes too long though I might just leave it, because it isn't causing any trouble. So I think I will just leave it.
Thank you