Click on the text you want to edit. A selection box will appear on top of the text.

You can edit the text color, size, and alignment by selecting the corresponding option in the toolbar above the text you're editing. You can also lock the text (pictured below).

You can also find additional settings by clicking " More".
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Once you're done editing the text, click anywhere on the canvas to deselect it.

Select the text you want to delete.

Click the 'More' option in the toolbar above the text and select 'Delete'. Or Select the content and press the delete key.