I have several dataframes in which I want to delete each row that matches a certain string. I used the following code to do it:

```
 df[!(regexpr("abc", df$V4) ==1),]

```

How can I delete the row that is following, e.g. if I delete row n as specified by the code above, how can I additionally delete row n+1?

My first try was to simply find out the indices of the desired rows, but that won't work, as I need to delete rows in different dataframes which are of different lengths. So the indices vary.

Thanks!