Remove a rest...

I hope this isn't covered elesewhere - I have looked. If anyone has a link, that's a fine answer.

I want to "left shift" a phrase into an existing rest, and alter the rhythm & duration of the last notes in the bar of the existing rest, but I can't work out how to do it. I can't edit the duration of the existing notes and keep them in the bar, and I can't delete the rest.

What to do?

Thanks in anticipation...