Help with removing extra legend elements in ggplot

I can't get the fine tuning right with my legend. I get an extra legend
element "10" which is the point size in my plot. Can someone help me get rid
of this extra element? Additionally I would also like to reduce the size of
the legend.

If you want to reproduce my figure you can  download my data in csv format
here
<https://github.com/scoyoc/EcoSiteDelineation/blob/master/VegNMDS_scores.csv

.

Here is my code...

veg.nmds.sc = read.csv("VegNMDS_scores.csv", header = T)

nmds.fig = ggplot(data = veg.nmds.sc, aes(x = NMDS1, y = NMDS2))
nmds.fig + geom_point(aes(color = VegType, shape = VegType, size = 10)) +
scale_colour_manual(name = "Vegetation Type",
                    values = c("blue", "magenta", "gray50", "red",
"cyan3",
                               "green4", "gold")) +
scale_shape_manual(name = "Vegetation Type", values = c(15, 16, 17, 18,
15, 16, 17)) +
theme_bw() +
theme(panel.background = element_blank(), panel.grid.major =
element_blank(),
      panel.grid.minor = element_blank(),
      legend.key = element_rect(color = "white")
      )

I have been messing around with

theme(..., legend.key.size = unit(1, "cm"))

but I keep getting the error "could not find function unit". I'm not sure
why, isn't unit supposed to be part of the legend.key argument?