What you are calling fillings is actually weeping mortar and it was a purposeful technique. To remove it i would think would be very costly and time consuming. I would call a mason to look at it..Maybe a solution would be to do a parge coat of stucco over to hide it.

It's a unique look. When I was growing up there was one contractor who used the technique in all the homes he built in my town. Painted all his home pure white.

It can be attractive on the right building.

Here is what I found online about removing it.

• I have been asked several times by homeowners whether weeping mortar can be removed. The short answer is, sure, all mortar can be removed (in theory). But I suppose the real answer depends on the strength of the mortar, and the workmanship of the mason who will be removing it. Weeping mortar would need to be carefully chipped off with a chisel. An errant chisel blow to the mortar could chip the face of the brick. Once the weeping mortar was removed, the mortar between the bricks would need to be cut back at least 1/2″ behind the face of the brick to allow the mason to repoint the mortar with a flush or concave tooling. Weeping mortar joints are typically wider than the narrow late-19th century “butter” joints, but it would not difficult for a mason who was removing mortar to cut into the brick using a grinder. Great care would need to be taken to prevent damage to the brick when removing weeping mortar. In addition, the stronger the weeping mortar, the harder it will be to remove. Weeping mortar was used on Depression-era and mid-century structures, so I would guess the mortar contained more cement than earlier mortar mixes, giving it strength and durability. So, yes, weeping mortar can be removed from brick, but as with most repair and rehabilitation projects, it is important to hire a skilled contractor with experience working on older structures.

$$$$$$$ to do that. it would be a good idea to post a picture of the whole house.