I have a large data set with thousands of columns. The column names include various unwanted characters as follows:

```
col1_3x_xxx
col2_3y_xyz
col3_3z_zyx

```

I would like to remove all character strings starting with "\_3" from all column names to be left with clean:

```
col1
col2
col3

```

What is the most efficient way to do this for 5000+ columns?