That's not how -d works.
For -d to work, you need the -l as well.
For -l to work, you need to specify the number behind it.
-dl5 would remove line 5 from the textfile. To know which line you want to delete, you search for it using $read(list.txt,nw,$2) and use $readn. $readn will return the number of the line that the last $read match was found.

The correct way to use it afterwards is to /write -dl $+ $readn list.txt

Nillens @
Nillen @