You can remove block title, subtitle, and a secondary title, as well as other attributes of your block in the Block settings menu.
To access it, hover any area of the block to activate the menu and click on the "gear" icon.
From here, you can change almost any attribute of the block including the title, the number of buttons, or other block-specific details.
To keep a title, click on the checkbox next to it:
Once you have done adding or removing the title and other text elements, click Save to confirm the changes.