Regarding the rumours of Jessica Jung being kicked out of SNSD, SM Entertainment released an official statement that SNSD Girls’ Generation will be promoting as 8 members with Jessica leaving the group.
On 30th September, SM Entertainment made an official statement regarding Jessica′s leave from the K-Pop idol girl group:
This spring, Jessica told the company that due to a personal situation, she will be stopping team promotions after the end of one more album promotions. Despite Jessica′s sudden announcement, the company and then SNSD members persistently worked hard and pondered on how to continue promotions in a good direction for SNSD.
However, before agreements could be made on rising conflicts regarding the priority and interests of SNSD promotions, Jessica began her fashion-related business, and a situation arose where it became difficult to continue as a team despite continuous discussions.
With this, the company decided it had to promote SNSD with eight members sooner than expected, and while it was discussing when to announce the news, Jessica posted her own perspective in the early morning.
From this point onwards, the company will unchangingly support and manage SNSD with eight members as well as Jessica′s personal activities.
Oh no 
In case you missed it, earlier today, Jessica posted on her Weibo, “I was excited about our upcoming fan events only to shockingly be informed by my company and 8 others that as of today, I′m no longer a member. I′m devastated – my priority and love is to serve as a member of GG, but for no justifiable reason, I am being forced out.”
Here:
Source: http://weibo.com/syjessica
At first, the above post made fans and netizens wonder if Jessica′s SNS account was hacked, as speculations rose on the issue. But havoc continued to ensue when the SNSD Girls’ Generation members were spotted upon arrival at the airport in China without Jessica. Furthermore, Dispatch later released a picture of Jessica arriving at Incheon airport, supposedly from New York, with rumoured boyfriend Tyler Kwon following closely behind.
The last time such catastrophe ripped through the K-Pop industry and caused a shitstorm of sorts was when Kris abruptly left EXO back in May. The difference is that Kris’ case was pretty black and white as he cited restrictions in terms of personal development plus the unfair distribution of wages.
(Source)