Is there a way to clear the query box?

[lucharo]

In a traditional editor, I'd go Cmd + A and then delete but in Harlequin that doesn't work

[tconbeer]

It does. Depending on your terminal and shell you may need to use ctrl+a to select all. You can also use ctrl+w to "close" the buffer -- if you only have 1 buffer open, it will clear it.