[DON'T DO THIS! It will break things (see below).]

If it's just a matter of making the default priority "invisible", you can try setting `org-priority-default` to 32 (the ASCII code for SPACE):

```lang-el
(setq-default org-priority-default 32)
```

That might break other things (e.g. trying to bump up the priority of a headline without a priority cookie using `org-priority-up` will signal an error). You can try to limit the damage by using `setq-local` in a buffer, so that only that buffer will see the breakage, but if you are dealing with multiple buffers (e.g. you want the agenda column view), then the `setq-default` is a blunt but more convenient instrument than using `setq-local` on each agenda file buffer.

Or you might not care about the `org-priority-(up|down)` breakage, but there might be other breakage as well - I don't know.

If you try it, reset `org-priority-default` to *its* default value to fix the breakage:

```lang-el
(setq-default org-priority-default 66)
```
where `66` is the ASCII code for `B`.

In summary: caveat emptor and do this at your own peril. There is no warranty at all.