Navigate to the location where python bin is available ,/usr/local/bin or /usr/bin/and Check the Version of python where your version is with 3.*

[root@linuxhelp1 bin]# python -V
Python 3.6.8

Now Unlink the python so that python 3 will be removed as the default version

[root@linuxhelp1 ~]# unlink python

Create a soft link with the python 2 Version

[root@linuxhelp1 bin]# ln -s python2 python

Now check the default Version of Python in your machine as follows:

[root@linuxhelp1 bin]# python -V
Python 2.7.5

Hence the result accomplished