Merge two partitions I've 2 partitions on my mac

350GB
150GB

What I need to do is to delete the 150GB permanently and put it back into the 350GB



Any help would be highly appreciated.
For merging partitions, it isn't possible, as partitions are not designed that way. You would have to delete the second partition (back up data if there is any on it), resize the first to fill the space, then restore the data of the second on the first. There unfortunately isn't any easy workaround to this.