You can select multiple photos at once from the grid view. In select mode, hold your finger on one photo then you can swipe across other photos to select multiple, then tap on the Trash Can at the bottom of the screen to delete them.
I may be misunderstanding your post, but deleting images from Lightroom will also delete them from any Lightroom albums that they are in. It would not, however, delete them from the Photos app if that's where they were originally imported from into Lightroom. Hopefully that's what you meant.