Same issue happens for me when using Astral Client texture pack. What I did to remove a texture pack was to download Zarchiver (Android only), went to Games > com.mojang > minecraftpe and deleted globalresourcepacks.json file by holding down it and tapping on delete. This removes all the texture packs you're using right now, but you can still put them back on in the "resource packs" menu on MCPE.
Kissa
Same issue happens for me when using Astral Client texture pack. What I did to remove a texture pack was to download Zarchiver (Android only), went to Games > com.mojang > minecraftpe and deleted globalresourcepacks.json file by holding down it and tapping on delete. This removes all the texture packs you're using right now, but you can still put them back on in the "resource packs" menu on MCPE.