
You can only delete custom spaces.
Sign in to Zoho One , click Directory icon on the top-right corner.
Click Applications, then click three dots icon next to the custom space you want to delete.

If the space you want to delete is not visible in the space bar, click 'three.dots.icon', then click 'three.dots.icon' next to the custom space you want to delete.
Click Delete Space.
Move the apps to a different space before deleting,
Bulk app assignment: Move all the apps in the current space to a different space. Click Select, then click the space you want to move the apps to.
Individual app assignment: Move each app to a different space. Click Select, then click the space you want to move it to. Repeat the same step for all apps listed.
Click Done.