Using pd.to_numeric
In [1079]: df[pd.to_numeric(df['id'], errors="coerce").notnull()]
Out[1079]:
id name
0 1 A
1 2 B
2 3 C
4 4 E
5 5 F
Using pd.to_numeric
In [1079]: df[pd.to_numeric(df['id'], errors="coerce").notnull()]
Out[1079]:
id name
0 1 A
1 2 B
2 3 C
4 4 E
5 5 F