using ggplot2 - removing solid black and gray line at bottom of my plot?

Question

Here is what my plot looks like

At the bottom of the plot has a dark black line, and below that there is a thick gray line.

Is there a way to remove these lines? And why are they there?

Here is a copy of my code for making this plot if that is helpful:

abstract_bing %>%
  ggplot(mapping = aes(x = url, y = sentiment)) +
  geom_col(show.legend = FALSE, fill = "#bc4b51") + #, position = "dodge") +
  geom_hline(aes(yintercept = 0)) + 
  labs(title = "", x = "", y = "") +
  theme(text = element_text(color = "#000000"),
        legend.position = "none",
        panel.background = element_rect(fill = "#E2E2E2"),
        panel.grid.minor = element_line(color = "#E2E2E2"),
        panel.grid.major = element_line(color = "#F6F6F6"))

Edit: Here is an example of what the data in the abstract_bing df looks like:

There are 9957 rows total

  url                                   negative positive sentiment
  <chr>                                    <dbl>    <dbl>     <dbl>
1 https://pubmed.ncbi.nlm.nih.gov/3382~        0        5         5
2 https://pubmed.ncbi.nlm.nih.gov/3462~        2        3         1
3 https://pubmed.ncbi.nlm.nih.gov/3469~        2        7         5
4 https://pubmed.ncbi.nlm.nih.gov/3470~        4        1        -3
5 https://pubmed.ncbi.nlm.nih.gov/3479~        1        3         2
6 https://pubmed.ncbi.nlm.nih.gov/3485~        7        3        -4

Essentially I am using x = url to have a bar for each unique url that shows its respective sentiment value.