How can I crop the data points which lie inside polygon and plot

One way could be to convert the points and polygon to sf objects, crop the points, then turn the data back into a tibble.

library(sf)
library(tidyverse)
library(gridExtra)

set.seed(345)

tbl <- tibble(x = runif(100),
              y = runif(100))

poly <- tibble(
  A = c(0.5, 0),
  B = c(1, 0.5),
  C = c(0.5, 1),
  D = c(0, 0.5)
)

# Convert tbl to sf object.
tbl_sf <- sf::st_as_sf(tbl, coords = c("x", "y"))

# Convert polygon to sf polygon.
poly_sf <- as.data.frame(t(poly)) %>%
  dplyr::rename(x = V1, y = V2) %>%
  sf::st_as_sf(coords = c("x", "y")) %>%
  dplyr::summarise() %>%
  sf::st_cast("POLYGON") %>%
  sf::st_convex_hull()

# Keep only points inside the polygon.
points <- sf::st_intersection(tbl_sf, poly_sf) %>%
  
# Get coordinates and convert back to tibble.
  sf::st_coordinates() %>%
  as_tibble() %>%
  dplyr::rename(x = X, y = Y)

before <- ggplot(data = tbl,
                 aes(x = x,
                     y = y)) +
  geom_point() +
  theme_bw() +
  coord_equal() +
  ggtitle("Before")

after <- ggplot(data = points,
                aes(x = x,
                    y = y)) +
  geom_point() +
  theme_bw() +
  coord_equal() +
  ggtitle("After")

grid.arrange(before, after, ncol = 2)

Output