diff --git a/demo/demo.py b/demo/demo.py
deleted file mode 100644
index bce8a1e..0000000
--- a/demo/demo.py
+++ /dev/null
@@ -1,29 +0,0 @@
-import startinpy
-import numpy as np
-import json
-import laspy
-
-las = laspy.read("/Users/hugo/data/ahn4/crop.laz")
-d = np.vstack((las.x, las.y, las.z, las.classification)).transpose()
-d100 = d[::10000] #-- thinning
-
-dt = startinpy.DT(extra_attributes=True)
-for each in d100:
-    dt.insert_one_pt(each[0], each[1], each[2], classification=each[3])
-
-# a = {'intensity': 155.5, 'reflectance': 111, 'hugo': True}
-# dt.set_attribute(50, json.dumps(a))
-
-# print("# vertices:", dt.number_of_vertices())
-# print("# triangles:", dt.number_of_triangles())
-
-print(dt)
-
-# a = dt.get_attribute(41)
-# print("=>", json.loads(a))
-
-i = dt.attributes('classification').astype(int)
-# print(np.nanmean(i))
-print(i)
-
-# print("all extra attributes:", dt.list_all_attributes())
\ No newline at end of file
diff --git a/demo/demo2.py b/demo/demo2.py
deleted file mode 100644
index d7a99fc..0000000
--- a/demo/demo2.py
+++ /dev/null
@@ -1,28 +0,0 @@
-import startinpy
-import numpy as np
-import json
-import laspy
-
-las = laspy.read("../data/small.laz")
-
-#-- read intensity and store it as extra_attribute in the startinpy DT
-d = np.vstack((las.x, las.y, las.z, las.intensity)).transpose()
-
-dt = startinpy.DT(extra_attributes=True)
-for each in d:
-    dt.insert_one_pt(each[0], each[1], each[2], intensity=each[3])
-
-a = {'intensity': 155.5, 'reflectance': 111, 'isvisited': True}
-dt.set_attribute(50, json.dumps(a))
-
-print(dt)
-
-print("all extra attributes:", dt.list_attributes())
-
-a = dt.get_attribute(50)
-print("=>", json.loads(a))
-a = dt.get_attribute(49)
-print("=>", json.loads(a))
-
-i = dt.attributes('intensity')
-print(i)
\ No newline at end of file
diff --git a/demo/demo3.py b/demo/demo3.py
deleted file mode 100644
index 268d4e6..0000000
--- a/demo/demo3.py
+++ /dev/null
@@ -1,35 +0,0 @@
-import startinpy
-import numpy as np
-
-#-- generate 100 points randomly in the plane
-rng = np.random.default_rng()
-pts = rng.random((100, 3))
-pts = pts * 100
-
-dt = startinpy.DT()
-dt.insert(pts)
-
-#-- remove vertex #4
-try:
-    dt.remove(4)
-except Exception as e:
-    print(e)
-
-print("# vertices:", dt.number_of_vertices())
-print("# triangles:", dt.number_of_triangles())
-
-print("CH: ", dt.convex_hull())
-
-print(dt.is_triangle([4, 12, 6]) )
-print(dt.is_triangle([5, 12, 6]) )
-
-print("--- /Points ---")
-for each in dt.points:
-    print(each)
-print("--- Points/ ---")
-
-alltr = dt.triangles
-print(alltr[3])
-
-zhat = dt.interpolate({"method": "TIN"}, [[55.2, 33.1]])
-print("result: ", zhat[0])