How to hide place names on the map

I have successfully found the place I need on the map, but the map also shows the names of many places in other countries. How do I get a map that does not display the place names, so as to highlight the places I marked.
Thank you very much. Below is my R code:
myMap <- get_map(location=myLocation, source="stamen", maptype="terrain-background", crop=FALSE)
mymarkers <- read.delim('D:/my.txt', header=T)
ggmap(myMap) + geom_point(aes(x=Long, y=Lat, color=population),
data=mymarkers, size=4) +
xlab("Longitude") + ylab("Latitude") +
scale_color_manual(values=c("#C88AFF", "#EB746B", '#FCCC00', "#1EB5B8")) +
theme(axis.text.x = element_text(color="black", size = 15),
axis.text.y = element_text(color = 'black', size = 15),
axis.title.x = element_text(color = 'black', size = 18),
axis.title.y = element_text(color = 'black', size = 18),
legend.position="none")