This is a really great question,let's get straight into it!
Over optimization of a link profile in most cases,not all essentially means that links have been built with an intention to manipulate Google!
Now most often it means there's an emphasis on what are known as money terms.So if a site owner is trying to rank for say 'SEO' he will be using that anchor text 'SEO' all across the web when building links.
So in other words he will have all of his links pointing at the same term!
The problem that comes about when you do this is that over time it will throw out the balance of your link profile.
And the biggest problem when your link profile becomes unbalanced is that it begins to send signals to Google,because it demonstrates intent that you are trying to manipulate the search results through artificial link building.
If you look at a natural link profile you will see that there is a variation of link ties.
You will see brand links,URL's coming from images and non related terms such as click here or view more!
But if 95 percent of your links are let's say (take the previous example) SEO,SEO and SEO then this can make your link profile look unnatural but let's face it most people know that it will look unnatural when they carry out such practices.
Now this is something which can result in all sorts of problems.It can result in a loos of rankings or worst case scenario you can be penalized and completely be De-indexed!
Now of course you would not want this to happen so if you are involved in link building it is really important that you diversify your anchor text.
You can't just keep repeating the same money terms over and over again!
When talking about fixing this problem there are 3 things that you can do.
And the 3rd option is to do both.
Let's start with deletion.This means going through your link profile and trying to remove as many bad links as possible.
Of course this is incredibly time consuming,in fact that you will find at some point that there are many of the links that you won't be able to remove so it can be a really tricky and complicated process.
OK so now let's talk about dilution.
Dilution essentially means just adding more good links and moving away from focusing in on money terms.
so it might be a good idea to start looking at adding brand links,non related terms,naked URL's,image links and any other type of link that does not contain your money terms!
Over time this will dilute your link profile and rebalance it in a way that will bring your keyword rich anchor text percentage down.
Now let us move on to the last step which is using both these methods at once.
That means trying to remove as many bad links as possible as well as adding more and more good links.
Conclusion Ok guys so that is it for this article,hope this helps you out.Stay safe!