You can delete blocks one at a time, or in batches via the timeline at the bottom of the Workspace. Hover your mouse over the block you want to delete. When you do, a menu will appear. Click on the trash can icon to delete the block.
Delete Multiple Blocks
To delete multiple Blocks, hold shift while selecting the Block you want to delete. Once you’re done selecting the Blocks you want to delete, click the trash icon from the menu that appears. You can also select all to delete all of the Blocks in your project.