clean: add targets prune command

Author: dsweber2

Makefile

@@ -35,6 +35,20 @@ explore-flu:
 
 explore: explore-covid explore-flu update-site netlify
 
+prune: prune-covid-prod prune-flu-prod prune-covid-explore prune-flu-explore
+
+prune-covid-prod:
+	export TAR_PROJECT=covid_hosp_prod; export BACKTEST_MODE=TRUE; Rscript -e "targets::tar_prune()"
+
+prune-flu-prod:
+	export TAR_PROJECT=flu_hosp_prod; export BACKTEST_MODE=TRUE; Rscript -e "targets::tar_prune()"
+
+prune-covid-explore:
+	export TAR_PROJECT=covid_hosp_explore; Rscript -e "targets::tar_prune()"
+
+prune-flu-explore:
+	export TAR_PROJECT=flu_hosp_explore; Rscript -e "targets::tar_prune()"
+
 commit-covid:
 	cd ../covid19-forecast-hub; \
 	git pull --rebase --autostash origin main; \