First of all, not all of the glass splatters are on one and the same layer. That means you can switch off a layer and there will already be fewer splatters.
If you want to reduce the splatters even more, you can do so as follows:
Select one of the layers that includes some of the glass splatters you want to remove. Add a mask to that layer by going to Layer > Layer Mask and choosing Reveal All. This will add a ‘white’ mask to the layer leaving its content visible. Alternatively, you can also click the little Add layer mask icon at the bottom of your layers panel.
With that done, go to the Brush Tool and select a black color.
Adjust the Opacity and Flow settings of the brush according to how many glass splatters and how strongly you want to edit them out.
If you want to remove a lot of the splatters, like completely, choose a brush with high Opacity and Flow. If you just want to make just some tweaks here and there, go for lower Opacity and Flow.
→ How To Change The Opacity Of Part Of An Image In Photoshop
Of course, you can also do the opposite and increase the amount of glass splatters! Just duplicate the splatter layers and tweak them around as you wish. You can scale them up or down, distort, warp and skew them.
Here’s one artist who created a beautiful artwork by increasing the amount of glass splatters and making them smaller.