Crthuky

My code and the related picture is shown. How to create a space between two child notes and leave node in tikzpicture?

beginfigure*
 centering
 begintikzpicture [baseline=-0.5ex] 
beginscope[sibling distance=10cm,
 every node/.style = ,shape=rectangle, rounded corners,
 draw, align=center, minimum size=.75cm,
 top color=white, align=center, bottom color=blue!20]]
 node (a) at (0,2) Goal : Company sustainability ;
 node (c2) at (-1,0) Governance;
 node (c3) at (0,0) Proper time;
 node (c1) at (-2,0)Skill Man power;
 node (c4) at (1,0) Logistic Support;
 node (c5) at (2,0) Work atmosphere;
 node (a1) at (-2,-2) Expected Salary;
 node (a2) at (-1,-2) Employee flexibility ;
 node (a3) at (0,-2) Boss Behaviour ;
 node (a4) at (1,-2) Project Presentation ;
 node (a5) at (2,-2) Switching Department;
endscope
draw (a)--(c1) (a) -- (c2) (a) -- (c3) (a)-- (c4) (a)-- (c5) 
(c1) -- (a1) (c1) -- (a2) (c1) -- (a3) (c1) -- (a4) (c1) -- (a5)
(c2) -- (a1) (c2) -- (a2) (c2) -- (a3) (c2) -- (a4) (c2) -- (a5)
(c3) -- (a1) (c3) -- (a2) (c3) -- (a3) (c3) -- (a4) (c3) -- (a5)
(c4) -- (a1) (c4) -- (a2) (c4) -- (a3) (c4) -- (a4) (c4) -- (a5)
(c5) -- (a1) (c5) -- (a2) (c5) -- (a3) (c5) -- (a4) (c5) -- (a5)
;
endtikzpicture
 captionCaption
 labelfig:my_label
endfigure*

With forest. (I most likely permuted your items, sorry for that!)

documentclass[border=3mm]standalone
usepackageforest
begindocument
beginforest
for tree=shape=rectangle, rounded corners,
 draw, align=center, minimum size=.75cm,
 top color=white, align=center, bottom color=blue!20,
 l sep+=5mm
[Goal : Company sustainability
 [Governance
 [Proper time]
 ] 
 [Skill Man power
 [Logistic Support]
 ] 
 [Work atmosphere
 [Expected Salary]
 ]
 [Employee flexibility
 [Boss Behaviour]
 ] 
 [Project Presentation 
 [Switching Department]
 ] 
] 
endforest
enddocument