Finding where to disable hyperlinks as the default is a prime example of a software company 'improving' the design of a successful program so that it is far more unusable than it was before. However, there is a way to do what you want - it used to be in the old Tools menu, now there's no such menu - so...
1. Click on the MS Button in the top left corner
2. At the bottom of the pop up, there are two rectangular 'boxes' - click on the one labeled "Excel options"
3. In the next pop up, select "Proofing" on the left, then on the right, click on the box labeled "AutoCorrect options"
4. In the next pop up, deselect "Replace as you type Internet and network paths with hyperlinks" and click OK
5. Click OK again
This should solve your problem but note that if you disable autocorrect links, you will have to right click on any you actually do want to create and add the address in the relevant pop up to create a link manually. Depends on which is the most work for you.