Mass change all links to open in same window

Hi There,

I need to change the links in all my blog posts that have all been set to "open in new window (blank)" to "open in the same window (self)"

I'm not a web expert, but I was hoping maybe there was some sort of code injection to do this for all my links. Otherwise it would be a mountain of a task to do this one by one across thousands of links. 

Can you share link to a blog post? We can help easier