Extracting data.frame from simple features object in R

To drop the geometry column, use st_drop_geometry():

library(sf)
nc <-  st_read(system.file("shape/nc.shp", package="sf"), quiet = TRUE)
nc_df2 <- nc %>% st_drop_geometry()
class(nc_df2)
#> [1] "data.frame"

Before st_drop_geometry() was added to the sf package (in November, 2018), one could produce the same result using the st_set_geometry() function, like this:

library(sf)
nc <-  st_read(system.file("shape/nc.shp", package="sf"), quiet = TRUE)
class(nc)
#> [1] "sf"         "data.frame"

nc_df <- nc %>% st_set_geometry(NULL)
class(nc_df)
#> [1] "data.frame"

Set the st_geometry property to NULL.

library(sf)
nc <-  st_read(system.file("shape/nc.shp", package="sf"), quiet = TRUE)
class(nc)
## [1] "sf"         "data.frame"
st_geometry(nc) <- NULL
class(nc)
## [1] "data.frame"

Also (though this won't remove the attr(nc, "sf_column"):

nc <-  st_read(system.file("shape/nc.shp", package="sf"), quiet = TRUE)
as.data.frame(nc)