feat: add llama stack rm command (#2127)

# What does this PR do?
[Provide a short summary of what this PR does and why. Link to relevant
issues if applicable.]

```
llama stack rm llamastack-test
```

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])
#225 

## Test Plan
[Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.*]

[//]: # (## Documentation)

llama_stack/cli/stack/remove.py

@@ -0,0 +1,116 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import argparse
+import shutil
+import sys
+from pathlib import Path
+
+from termcolor import cprint
+
+from llama_stack.cli.subcommand import Subcommand
+from llama_stack.cli.table import print_table
+
+
+class StackRemove(Subcommand):
+    """Remove the build stack"""
+
+    def __init__(self, subparsers: argparse._SubParsersAction):
+        super().__init__()
+        self.parser = subparsers.add_parser(
+            "rm",
+            prog="llama stack rm",
+            description="Remove the build stack",
+            formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+        )
+        self._add_arguments()
+        self.parser.set_defaults(func=self._remove_stack_build_command)
+
+    def _add_arguments(self) -> None:
+        self.parser.add_argument(
+            "name",
+            type=str,
+            nargs="?",
+            help="Name of the stack to delete",
+        )
+        self.parser.add_argument(
+            "--all",
+            "-a",
+            action="store_true",
+            help="Delete all stacks (use with caution)",
+        )
+
+    def _get_distribution_dirs(self) -> dict[str, Path]:
+        """Return a dictionary of distribution names and their paths"""
+        distributions = {}
+        dist_dir = Path.home() / ".llama" / "distributions"
+
+        if dist_dir.exists():
+            for stack_dir in dist_dir.iterdir():
+                if stack_dir.is_dir():
+                    distributions[stack_dir.name] = stack_dir
+        return distributions
+
+    def _list_stacks(self) -> None:
+        """Display available stacks in a table"""
+        distributions = self._get_distribution_dirs()
+        if not distributions:
+            print("No stacks found in ~/.llama/distributions")
+            return
+
+        headers = ["Stack Name", "Path"]
+        rows = [[name, str(path)] for name, path in distributions.items()]
+        print_table(rows, headers, separate_rows=True)
+
+    def _remove_stack_build_command(self, args: argparse.Namespace) -> None:
+        distributions = self._get_distribution_dirs()
+
+        if args.all:
+            confirm = input("Are you sure you want to delete ALL stacks? [yes-i-really-want/N] ").lower()
+            if confirm != "yes-i-really-want":
+                print("Deletion cancelled.")
+                return
+
+            for name, path in distributions.items():
+                try:
+                    shutil.rmtree(path)
+                    print(f"Deleted stack: {name}")
+                except Exception as e:
+                    cprint(
+                        f"Failed to delete stack {name}: {e}",
+                        color="red",
+                    )
+                    sys.exit(2)
+
+        if not args.name:
+            self._list_stacks()
+            if not args.name:
+                return
+
+        if args.name not in distributions:
+            self._list_stacks()
+            cprint(
+                f"Stack not found: {args.name}",
+                color="red",
+            )
+            return
+
+        stack_path = distributions[args.name]
+
+        confirm = input(f"Are you sure you want to delete stack '{args.name}'? [y/N] ").lower()
+        if confirm != "y":
+            print("Deletion cancelled.")
+            return
+
+        try:
+            shutil.rmtree(stack_path)
+            print(f"Successfully deleted stack: {args.name}")
+        except Exception as e:
+            cprint(
+                f"Failed to delete stack {args.name}: {e}",
+                color="red",
+            )
+            sys.exit(2)