I think he means he wants to make a backup of the current 'repo' setup, and restore it later.
In that case, you really need to look at yum usage, because there is no point in permanently disabling, or modifying the config. You can use:
yum --disablerepo=* --enablerepo=new_repo install openssl
To temporarily disable ALL repos, then immediately enable 'new_repo' and install openssl from it.
Note: When you put in your temporary repo to install the new OpenSSL, the format of the file is like this: