When you enchant boots (any) with soul speed and you run on soul sand, you cannot remove the boots until durability bar is full and boots aren't damaged anymore. Only way to take em off is to exit world and re enter the world. This in my opinion is a bug for the game.
Thank you for your report!
We're tracking this issue in MCPE-106367, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
-- I am a bot. This action was performed automatically! Please report any issues on Discord or Reddit