Data refresh not happening

Hello!

Brand new PowerBI user here.

I've been creating a dashboard on PowerBI desktop, linked to an Excel file saved on my laptop. I was trying to test the refresh function and wanted to do so by removing some cells from the source file. In my mind, when doing so and hitting refresh, what I'd then see in PowerBI desktop is my original source file minus the cells I've deleted (is this correct?). However, not only the visuals in the tiles don't change but also the source file in query mode still shows the cells I have deleted.

How do I referesh my report? What am I missing?

Thanks a lot in advance for the help!