Events on change save? And you could make a micro / nano flow to clear all the fields in one go.
If you want to delete all rows of a data grid set the selection option to multi in the properties of the datagrid. Add a select all button (choose between select all on page and select all rows) to the grid bar (is a default button).
You can make columns of a datagrid editable which would commit when leaving the field. This is not a best practice though because you cant trigger any event you would want to do beforehand, like validation.
Ps, your screenshot shows a dataview, not a datagrid
For saving without clicking save, make the Datagrid editable.
For deleting, I recommend creating a “delete all” microflow which retrieves the elements in the Datagrid, deletes them, and refreshes in client. You can then add a “delete all” button in the datagrid.