julia> deleteat!(df, findall(==(:C), df.group)[2])
7×2 DataFrame
Row │ group X
│ Symbol Int64
─────┼───────────────
1 │ A 101
2 │ A 102
3 │ B 103
4 │ B 104
5 │ C 105
6 │ C 107
7 │ C 108
Assumes that there is a second line that starts with C i.e. assumes there are at least two C
s in the group
column.