How to only show x axis labels that HAVE values, and remove ones that have nothing using facet_wrap ggplot?

I am graphing some data using facet_wrap and my x axis labels are ALOT. I wanted to remove the labels where no data exists to try and get rid of all the mess. But my facet_wrap graphs all have different x axis labels with values. So is there a function that only shows tick labels when a value exists, instead of manually defining what x-axis tick labels to include

Here is my dataframe:

df = structure(list(Method_Used = c("Animal_Borne_Acoustic", "Animal_Borne_Acoustic_Archival", 
"Animal_Borne_Archical", "Animal_Borne_Archical", "Animal_Borne_Archical", 
"Animal_Borne_Archical", "Animal_Borne_Archical", "Animal_Borne_Archical", 
"Animal_Borne_Archical", "Animal_Borne_Archival_PIT", "Animal_Borne_Archival_Satellite", 
"Animal_Borne_Satellite", "Animal_Borne_Satellite_Archival", 
"Animal_Borne_Satellite_Archival", "BRUV_Acoustic", "BRUV_Acoustic", 
"BRUV_Acoustic_Satellite", "Controlled_Acoustic", "Controlled_Acoustic", 
"Controlled_Archical", "Controlled_Satellite", "Drone_Acoustic", 
"Stationary_Acousitc_PIT", "Stationary_Acoustic", "Stationary_Acoustic", 
"Stationary_Acoustic", "Stationary_Acoustic", "Stationary_Acoustic", 
"Stationary_Acoustic_Archival", "Stationary_Acoustic_Archival", 
"Stationary_Acoustic_Archival", "Stationary_Acoustic_Archival", 
"Stationary_Acoustic_PIT", "Stationary_Acoustic_Radio", "Stationary_Acoustic_Radio_PIT", 
"Stationary_Archical", "Stationary_Archical", "Stationary_Archical", 
"Stationary_PIT", "Stationary_Radio", "Stationary_Radio_PIT", 
"Stationary_Satellite", "Stationary_Satellite"), Water_Type = c("Saltwater", 
"Saltwater", "Freshwater", "Saltwater", "Saltwater", "Saltwater", 
"Saltwater", "Saltwater", "Saltwater", "Saltwater", "Saltwater", 
"Saltwater", "Saltwater", "Saltwater", "Saltwater", "Saltwater", 
"Saltwater", "Freshwater", "Saltwater", "Saltwater", "Saltwater", 
"Saltwater", "Freshwater", "Brackish", "Freshwater", "Saltwater", 
"Saltwater", "Saltwater", "Saltwater", "Saltwater", "Saltwater", 
"Saltwater", "Freshwater", "Freshwater", "Freshwater", "Saltwater", 
"Saltwater", "Saltwater", "Freshwater", "Freshwater", "Freshwater", 
"Saltwater", "Saltwater"), Taxa = c("Reptilia", "Chondrichthyes", 
"Phocidae", "Cetacea", "Chondrichthyes", "Mollusca", "Phocidae", 
"Reptilia", "Teleostei", "Reptilia", "Reptilia", "Chondrichthyes", 
"Chondrichthyes", "Phocidae", "Chondrichthyes", "Teleostei", 
"Chondrichthyes", "Chondrostei", "Teleostei", "Cetacea", "Phocidae", 
"Chondrichthyes", "Teleostei", "Teleostei", "Teleostei", "Chondrichthyes", 
"Decapoda", "Teleostei", "Chondrichthyes", "Decapoda", "Gastropoda", 
"Teleostei", "Teleostei", "Teleostei", "Teleostei", "Gastropoda", 
"Reptilia", "Teleostei", "Teleostei", "Teleostei", "Teleostei", 
"Cetacea", "Phocidae"), total_count = c(1L, 1L, 1L, 7L, 6L, 1L, 
2L, 5L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 1L, 5L, 1L, 1L, 1L, 
1L, 2L, 4L, 1L, 1L, 12L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 2L, 1L, 1L, 1L)), class = c("tbl_df", "tbl", "data.frame"
), row.names = c(NA, -43L))

This is the code for my graph:

Taxa_Plot = ggplot(
data = df,
aes(x = Method_Used, y = total_count)) +
geom_col() +
theme_classic() +
facet_wrap(~Water_Type) +
# increase the text size on x and y axis
theme( axis.text.x = element_text(size = 15, angle = 45, hjust = 1),
axis.text.y = element_text(size = 15))
Taxa_Plot

Any ideas?

You can use scales = "free_x" within facet_wrap().

library(tidyverse)

ggplot(
  data = df,
  aes(x = Method_Used, y = total_count)) +
  geom_col() +
  theme_classic() +
  facet_wrap(~Water_Type, scales = "free_x") +
  theme( axis.text.x = element_text(size = 15, angle = 45, hjust = 1),
         axis.text.y = element_text(size = 15))

<hr>

You can use facet_grid with space = "free_x" to make the bars equal in size.

ggplot(
  data = df,
  aes(x = Method_Used, y = total_count)) +
  geom_col() +
  theme_classic() +
  facet_grid(~Water_Type, scales = "free_x", space = "free_x") +
  theme( axis.text.x = element_text(size = 15, angle = 45, hjust = 1),
         axis.text.y = element_text(size = 15))