Removing lesson counter text under section header

Hi.

Just went to edit a course and I found this text

"lesson 1 D 8"

 

Under each page header. I take it to be "lesson 1 of 8" as on the next page is 2 D 8 etc. I cannot see when I go into edit - and I would very much like not to have it showing in the end product...

 

Any suggestions on how I can remove it?

Thanks!