Depending on the issue and excess length you might bend the cable out of the way, you might shorten it, or you might release and reattach it.
In this case the cable could be released and pulled down more, behind the clamping plate there is a little groove that the cable is not currently sitting in, see the extract below from the dealer's manual for R3000 derailleurs, showing the cable path.
If then it still hits something you could shorten it a touch (if you have the means to re-crimp the end). The blue coating is a friction reducing coating, it doesn't do anything at this end of the system so that doesn't matter.
You want to shift down into the lowest setting on the derailleur before releasing the cable. You can check if the derailleur is lined up correctly in height and angle and that the support screw is engaged. You can refer to the sections in the dealer's manual below, and/or online guides.
I wouldn't bother to mark the bolt before releasing, you'll need to release it as far as necessary and after reattaching it could be in a different position when it is fastened tightly enough. With the cable tucked underneath properly it will probably allow the bolt to screw in further before tight.
Any barrel adjuster should be easily visible along the housing. If you don't have one that is a little more challenging, you'll have to pull some tension on the cable as you attach it. One hack is to tighten the low limit screw by a known amount (like one turn) before attaching the cable. then when cable is secure, releasing the low limit screw by the same known amount, allowing the cable to tighten.
