I am having issues with my layers. I am using QGIS v3.2, and have been stuck on this issue for a while now. I using OGA License blocks to plot certain points at sea. These license blocks follow a standard square shape e.g 4km x 4km. However, some of these blocks have multiple irregular shapes within. the Figure below identifies examples of standard squares and squares with irregular shapes within.
I need these irregular shapes deleted. The process I have used is to --> download shapefile with data. when I load the shapefile into QGIS and open the attribute table none of the column headings relate to causing the irregular shapes. I have attempted to delete the irregularities by --> toggle editing --> selection by feature and selecting the features (figure 2)

When I delete them however, although they delete and erase the irregular blocks they also erase the joining line between each 4km by 4km blocks which I need, as seen in figure 3
Does anyone know how to solve the issue of deleting the irregular shapes within the blocks whilst at the same time not deleting the boarder to each 4km by 4km block?