Landscaping Bugs or need advice

, I have Landscape spikes. I can delete it but when I go to flaten it out , nothing. I can sculpt but the spike stays all the way to the sky , I have tried to move the road splines away from it and it doesnt work? Any idea ?

(second pic) Ive tried everything I can think of .My splines will do this odd thing where the ground shows up under neath it. I have tried to play with the angle and the curve weather it be up or down etc. Its still there. How do I get rid of the Ground poking through my splines like this ? ( see pic)

https://preview.redd.it/i4aqa74egcyd1.png?width=858&format=png&auto=webp&s=92b1ff7c854427562b5a8e37f7a9d334fba3342e

https://preview.redd.it/fvqfkv3egcyd1.png?width=809&format=png&auto=webp&s=a4d26523b4597f24e88cdf9793bc23d27087e032