How to remove a particular portion from a plot?

Hi i have generated a alpha diversity plot from using the following code and getting a plot like the following.
CODE:

#plot alpha diversity index
alpha_sweden <- plot_richness(physeq_rarefied, x="type", measures="Shannon") + 
  stat_compare_means(method = "wilcox.test") +
  geom_boxplot(aes(fill = type), notch = TRUE, outlier.size = -1) + 
  scale_fill_manual(values = c("skyblue", "hotpink"))+
  labs(x= "Sample types", y= "Shannon Diversity Index", fill ="Groups") +
theme(legend.position = element_blank(), axis.text.x = element_blank())

alpha_erp002469_sweden$layers[1] <- NULL

#export alpha diversity index
tiff(filename = "alpha_diversity_plot.tiff", width = 30, height = 30, units = "cm", res = 1200)
alpha_erp002469_sweden
dev.off()

PLOT:


Can you please tell me how can I remove that "Shannon" heading from the plot?

Thanks,
DC7

It's hard to tell for sure without a reprex (short for reproducible example), as I'm not sure where plot_richness() comes from (it's not a ggplot2 function, I imagine it's a helper function from another package).

There's a nice FAQ on how to do a minimal reprex for beginners, below:

From the look of it, "Shannon" is the label for the facet of the plot (even though you don't actually have any other panels there, the default theming for facets have the grey strip right on top of the plot). So, you'd have to work with the strip.* theme arguments in order to change the appearance of that from its default label with plot_richness().

Depending on how plot_richness() works, I don't know whether or not you'll be able to modify the labeller() arguments.