Stucco is a very hard material because it is usually made up of cement based products, which can present some problems on dealing with rough stucco issues. Grinding is one of those "issues" that can seem to be difficult but it can be done with the right tools and knowledge.
Can You Grind Stucco Down?
The short answer to this question is yes, stucco can be ground down if you use a diamond or carbide grinding wheel. These are the only types of blades that can handle such a hard material and actually remove material.
Grinding stucco produces a huge amount of dust and flying particles so be sure you have a respirator, eye/face protection, gloves and any other protective equipment you may need. A fan can also help with the dust.
Keep a good grip on your angle grinder, as grinding stucco can make the grinder kick pretty good and possible fly out of your hands.
What Grinding Wheels/Stones Can I Use?
As I mentioned above, the only grinding wheels that will work to grind stucco is either a diamond or carbide coated blade. These can come in a couple of different shapes though and have advantages because of their shapes.
Diamond Cup Wheels: These are wheels that are cupped in shape (hence the name) that are covered in tiny diamond grit material and really accel at grinding the surface of the stucco (flat grinding) and provide the highest grinding surface area.
These can take off a good amount of material in a short amount of time, especially a new wheel that has never been used, so pay attention to how much you're taking off.
You can find these almost anywhere these days but I really like the selection and prices they have on Amazon, as I have found the right size for my angle grinder (diameter and arbor size) nearly every time. Home Depot and Lowes will usually also carry these but from what I've noticed, the selection is limited (in store) so you might pay a little more for one but on the flip side, no wait time.
Diamond Cutting Wheels: Diamond cutting wheels are really made for cutting but I have used them for grinding too.
Like the cupped wheels, they usually have a diamond or carbide grit embedded into the blades surface but these are mounted on the outside of the blade only.
The diamond cutting wheels wont grind flat on the surface like the cupped wheels will but you can hold your grinder parallel with the wall and still grind off material, just not as much surface area will be ground off at one time.
Since you are grinding a very concentrated area, the stucco material will come off very quickly, so you need to keep an eye on how much you are removing and keep the grinder moving, in some cases. I also like to get these from Amazon myself but I have bought them from Home Depot and Lowes in the past before.
The diamond cutting blade that is pictured above works best, from what I have found. They also sell segmented diamond cutting blades that will work but not nearly as well, in my experience.
Grinding Stone: These are handheld grinding stones that have a handle and are used manually to grind off stucco material and are sometimes referred to as "concrete rubbing bricks".
Using one of these is the safest way to grind down stucco but can take quite a while to make any significant difference.
I usually used these handheld grinding stones when I want to take off smaller bits of stucco or concrete or when no power is available. These do take some time to remove materials, compared to the diamond wheels we looked at but still have their place in some instances.
I found a few different rub bricks on Amazon's website and a few choices at Home Depot and Lowes as well but having them stocked in the store was an issue I ran into personally, so make sure they have them in stock if you plan on getting them in-store.
When Would I Need To Grind Stucco?
The question of whether or not stucco can be ground down is usually accompanied by the question of why would I need to grind down the stucco anyways.
Usually the answer to this is when you have an area of stucco that was done improperly and is too rough or too high in spots, then you will need to grind it down in some fashion in order to make it blend in better. This is almost exclusively the case when grinding stucco.